This article shows the difference between the default preferences of Firefox 149.0 beta 9 and Firefox 148.0.2. The diff table below is generated using my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 149.0 beta 9Firefox 148.0.2
accessibility.ariaNotify.enabled undefined false
app.releaseNotesURL https://www.mozilla.org/%LOCALE%/firefox/%VERSION%/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-desktop&utm_campaign=whatsnew https://www.mozilla.org/%LOCALE%/firefox/%VERSION%beta/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-desktop&utm_campaign=whatsnew
app.releaseNotesURL.aboutDialog https://www.mozilla.org/%LOCALE%/firefox/%VERSION%/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-desktop&utm_campaign=about-dialog https://www.mozilla.org/%LOCALE%/firefox/%VERSION%beta/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-desktop&utm_campaign=about-dialog
app.update.channel release beta
app.update.url.details https://www.mozilla.org/%LOCALE%/firefox/notes https://www.mozilla.org/%LOCALE%/firefox/beta/notes
app.update.url.manual https://www.mozilla.org/%LOCALE%/firefox/new?reason=manual-update https://www.mozilla.org/%LOCALE%/firefox/beta?reason=manual-update
browser.aiwindow.apiKey undefined
browser.aiwindow.chatStore.loglevel Error undefined
browser.aiwindow.enabled false undefined
browser.aiwindow.endpoint https://mlpa-prod-prod-mozilla.global.ssl.fastly.net/v1 undefined
browser.aiwindow.firstrun.autoAdvanceMS 3000 undefined
browser.aiwindow.firstrun.modelChoice undefined
browser.aiwindow.memories false undefined
browser.aiwindow.memoriesLogLevel Warn undefined
browser.aiwindow.model qwen3-235b-a22b-instruct-2507-maas undefined
browser.aiwindow.preferences.enabled false undefined
browser.ipProtection.autoRestoreEnabled undefined false
browser.ipProtection.bandwidth.enabled undefined true
browser.ipProtection.bandwidthThreshold undefined 0
browser.ipProtection.egressLocationEnabled undefined false
browser.ipProtection.everOpenedPanel undefined false
browser.ipProtection.features.siteExceptions false true
browser.ipProtection.hasUpgraded undefined false
browser.ipProtection.panelOpenCount 0 undefined
browser.ipProtection.siteExceptionsHintsEnabled undefined true
browser.ipProtection.userEnableCount undefined 0
browser.ipProtection.variant undefined
browser.ml.smartAssist.apiKey undefined
browser.ml.smartAssist.enabled false undefined
browser.ml.smartAssist.endpoint undefined
browser.ml.smartAssist.model undefined
browser.ml.smartAssist.overrideNewTab false undefined
browser.newtabpage.activity-stream.discoverystream.imageProxy.enabled false true
browser.newtabpage.activity-stream.discoverystream.personalization.enabled false undefined
browser.newtabpage.activity-stream.discoverystream.personalization.modelKeys nb_model_arts_and_entertainment, nb_model_autos_and_vehicles, nb_model_beauty_and_fitness, nb_model_blogging_resources_and_services, nb_model_books_and_literature, nb_model_business_and_industrial, nb_model_computers_and_electronics, nb_model_finance, nb_model_food_and_drink, nb_model_games, nb_model_health, nb_model_hobbies_and_leisure, nb_model_home_and_garden, nb_model_internet_and_telecom, nb_model_jobs_and_education, nb_model_law_and_government, nb_model_online_communities, nb_model_people_and_society, nb_model_pets_and_animals, nb_model_real_estate, nb_model_reference, nb_model_science, nb_model_shopping, nb_model_sports, nb_model_travel undefined
browser.newtabpage.activity-stream.discoverystream.personalization.override false undefined
browser.newtabpage.activity-stream.discoverystream.recs.personalized false undefined
browser.newtabpage.activity-stream.discoverystream.refinedCardsLayout.enabled true undefined
browser.newtabpage.activity-stream.discoverystream.sections.customizeMenuPanel.enabled false true
browser.newtabpage.activity-stream.discoverystream.sections.layout undefined 7-double-row-2-ad
browser.newtabpage.activity-stream.discoverystream.sections.personalization.enabled false true
browser.newtabpage.activity-stream.discoverystream.spocs.personalized false undefined
browser.newtabpage.activity-stream.feeds.recommendationprovider true undefined
browser.newtabpage.activity-stream.privacyInfo.url undefined https://support.mozilla.org/1/firefox/149.0/Linux/en-US/sponsor-privacy
browser.newtabpage.activity-stream.support.url https://support.mozilla.org/1/firefox/148.0.2/Linux/en-US/new-tab https://support.mozilla.org/1/firefox/149.0/Linux/en-US/new-tab
browser.newtabpage.activity-stream.weather.placement header undefined
browser.preferences.aiControls.showUnavailable undefined false
browser.safebrowsing.globalCache.enabled undefined false
browser.safebrowsing.provider.google5.lists goog-badbinurl-proto,goog-downloadwhite-proto,goog-phish-proto,googpub-phish-proto,goog-malware-proto,goog-unwanted-proto,goog-harmful-proto goog-badbinurl-proto,goog-downloadwhite-proto,goog-phish-proto,googpub-phish-proto,goog-malware-proto,goog-unwanted-proto,goog-harmful-proto,goog-globalcache-proto
browser.safebrowsing.provider.mozilla.lists base-track-digest256,mozstd-trackwhite-digest256,google-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256,harmfuladdon-block-digest256,harmfuladdon-entitylist-digest256 base-track-digest256,mozstd-trackwhite-digest256,google-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256,harmful-addon-block-digest256,harmful-addon-entitylist-digest256
browser.safebrowsing.realTime.enabled undefined false
browser.safebrowsing.realTime.simulation.cacheTTLSec undefined 300
browser.safebrowsing.realTime.simulation.enabled undefined false
browser.safebrowsing.realTime.simulation.hitProbability undefined 100
browser.safebrowsing.realTime.simulation.noiseEntryCount undefined 4
browser.search.widget.new false true
browser.smartwindow.apiKey undefined
browser.smartwindow.chatHistory.loglevel undefined Error
browser.smartwindow.chatStore.loglevel undefined Error
browser.smartwindow.enabled undefined false
browser.smartwindow.endpoint undefined https://mlpa-prod-prod-mozilla.global.ssl.fastly.net/v1
browser.smartwindow.firstrun.autoAdvanceMS undefined 3000
browser.smartwindow.firstrun.hasCompleted undefined false
browser.smartwindow.firstrun.modelChoice undefined
browser.smartwindow.memories undefined true
browser.smartwindow.memoriesLogLevel undefined Warn
browser.smartwindow.model undefined
browser.smartwindow.preferences.endpoint undefined
browser.smartwindow.smartbarMentions.loglevel undefined Error
browser.tabs.context.close-duplicate.enabled true undefined
browser.tabs.dragDrop.multiselectStacking true undefined
browser.tabs.remoteSVGIconDecoding false true
browser.tabs.splitView.enabled false true
browser.tabs.splitview.hasUsed undefined false
browser.urlbar.amp.minKeywordLength undefined 0
browser.urlbar.mdn.minKeywordLength undefined 0
browser.urlbar.mentions.maxResults undefined 5
browser.urlbar.quicksuggest.ampTopPickUseNovaIconSize undefined false
browser.urlbar.switchTabs.searchAllContainers true undefined
browser.urlbar.trustPanel.featureGate false true
cookiebanners.ui.desktop.cfrVariant 0 undefined
devtools.application.selectedSidebar undefined service-workers
devtools.application.sessionHistory.enabled undefined false
devtools.debugger.features.stylesheets-in-debugger undefined false
devtools.target-switching.server.enabled true undefined
devtools.webconsole.codemirrorNext undefined false
distribution.about undefined Mozilla Firefox Official Build
distribution.id undefined mozilla-official
distribution.version undefined 1.0
dom.arena_allocator.enabled true undefined
dom.closewatcher.enabled false true
dom.customHighlightAPI.enabled true undefined
dom.element.popoverhint.enabled undefined true
dom.forms.alpha.enabled undefined false
dom.forms.colorspace.enabled undefined true
dom.hidden_until_found.enabled true undefined
dom.input.showPicker_datalist.enabled false true
dom.keyboardevent.init_key_event.enabled false undefined
dom.media.pseudo-classes.enabled undefined false
dom.quotaManager.temporaryStorage.clearTemporaryOriginsUsingOriginCache undefined true
dom.reporting.enabled false true
dom.reporting.header.enabled false true
dom.script_loader.experimental.navigation_cache.check_memory_pressure undefined true
dom.security.credentialmanagement.digital.enabled undefined false
dom.select.customizable_select.enabled undefined false
dom.storage_access.forward_declared.enabled false undefined
dom.storage_access.forward_declared.lifetime 900 undefined
dom.w3c_pointer_events.getcoalescedevents_only_in_securecontext true undefined
dom.webnotifications.block_if_on_safebrowsing undefined true
dom.window.named_properties_object.legacy_own_property_keys undefined false
extensions.formautofill.addresses.supportedCountries US,CA,GB,FR,DE,BR,ES,JP US,CA,GB,FR,DE,BR,ES,JP,AT,IN,IT,PL,AU
extensions.openPopupWithoutUserGesture.enabled false true
extensions.webcompat-reporter.enabled false true
extensions.webcompat.enable_interventions undefined true
extensions.webcompat.enable_shims undefined true
extensions.webcompat.useScriptingAPI true undefined
extensions.webextensions.allow_executeScript_in_moz_extension undefined true
extensions.webextensions.legacyStructuredCloneBehavior undefined true
extensions.webextensions.pageActionIconDarkModeFilter.enabled undefined true
gfx.canvas.max-area undefined 1073741823
gfx.canvas.max-size 32767 65535
gfx.max-texture-size 32767 65535
gfx.webrender.precise-conic-gradients true undefined
gfx.webrender.precise-conic-gradients-swgl true undefined
gfx.webrender.precise-radial-gradients true undefined
gfx.webrender.precise-radial-gradients-swgl true undefined
image.jxl.enabled false undefined
javascript.options.experimental.dictionary_teleporting true undefined
javascript.options.experimental.math_sumprecise true undefined
javascript.options.experimental.shadow_realms false undefined
javascript.options.experimental.uint8array_base64 true undefined
javascript.options.experimental.upsert true undefined
javascript.options.objectfuse_for_all_protos undefined true
javascript.options.use_js_microtask_queue true undefined
javascript.options.wasm_compact_imports undefined false
javascript.options.wasm_lazy_tiering_for_gc true undefined
layout.css.color-mix-multi-color.enabled undefined false
layout.css.text-box.enabled undefined false
mathml.adjust_default_lspace_rspace_for_positive_scriptlevel.disabled undefined true
mathml.font_family_math.enabled false true
media.captureStream.enabled undefined true
media.gmp-manager.cert.requireBuiltIn true undefined
media.gmp-manager.checkContentSignature true undefined
media.mediasource.mp4.enabled true undefined
media.mediasource.webm.enabled true undefined
mousewheel.allow_scrolling_more_than_one_page undefined false
network.backgroundfilesaver.async_copy_chunk_size undefined 1048576
network.dns.high_priority_dispatch undefined true
network.dnsCacheEntries 800 1600
network.http.fallback_to_net_parse_ct undefined true
network.http.http3.0rtt_timeout undefined 5000
network.lna.etp.enabled false true
network.socket.allowed_nonlocal_domains undefined
network.socket.prioritize_runnables undefined true
network.ssl_tokens_cache_records_per_entry 2 10
network.standard_content_type_parsing.response_headers true undefined
network.trr.allow_default_http3_first undefined false
network.trr.force_http3_first undefined false
network.trr.high_priority_events undefined true
network.trr.parse_on_socket_thread undefined true
pdfjs.enableHWA false true
pdfjs.enableSplitMerge undefined false
permissions.desktop-notification.telemetry.siteCategories undefined {"facebook.com":"social","instagram.com":"social","twitter.com":"social","x.com":"social","tiktok.com":"social","linkedin.com":"social","reddit.com":"social","pinterest.com":"social","snapchat.com":"social","tumblr.com":"social","slack.com":"chat_communication","discord.com":"chat_communication","teams.microsoft.com":"chat_communication","zoom.us":"chat_communication","whatsapp.com":"chat_communication","telegram.org":"chat_communication","messenger.com":"chat_communication","skype.com":"chat_communication","signal.org":"chat_communication","viber.com":"chat_communication","mail.google.com":"email","gmail.com":"email","outlook.com":"email","outlook.live.com":"email","mail.yahoo.com":"email","yahoo.com":"email","protonmail.com":"email","aol.com":"email","icloud.com":"email","zoho.com":"email","youtube.com":"media_streaming","netflix.com":"media_streaming","twitch.tv":"media_streaming","hulu.com":"media_streaming","disneyplus.com":"media_streaming","hbomax.com":"media_streaming","primevideo.com":"media_streaming","crunchyroll.com":"media_streaming","paramountplus.com":"media_streaming","spotify.com":"media_streaming","soundcloud.com":"media_streaming","pandora.com":"media_streaming","tv.apple.com":"media_streaming","steampowered.com":"gaming","steamcommunity.com":"gaming","store.epicgames.com":"gaming","roblox.com":"gaming","playstation.com":"gaming","xbox.com":"gaming","nintendo.com":"gaming","battle.net":"gaming","itch.io":"gaming","chess.com":"gaming","calendar.google.com":"calendar","outlook.live.com":"calendar","calendar.yahoo.com":"calendar","calendar.com":"calendar","drive.google.com":"productivity_collaboration","docs.google.com":"productivity_collaboration","sheets.google.com":"productivity_collaboration","office.com":"productivity_collaboration","onedrive.live.com":"productivity_collaboration","dropbox.com":"productivity_collaboration","box.com":"productivity_collaboration","notion.so":"productivity_collaboration","trello.com":"productivity_collaboration","asana.com":"productivity_collaboration","monday.com":"productivity_collaboration","atlassian.com":"productivity_collaboration","gitlab.com":"productivity_collaboration","bitbucket.org":"productivity_collaboration","miro.com":"productivity_collaboration","figma.com":"productivity_collaboration","cnn.com":"news_publishers","nytimes.com":"news_publishers","bbc.com":"news_publishers","theguardian.com":"news_publishers","washingtonpost.com":"news_publishers","foxnews.com":"news_publishers","reuters.com":"news_publishers","apnews.com":"news_publishers","bloomberg.com":"news_publishers","wsj.com":"news_publishers","usatoday.com":"news_publishers","nbcnews.com":"news_publishers","abcnews.go.com":"news_publishers","cbsnews.com":"news_publishers","npr.org":"news_publishers","time.com":"news_publishers","newsweek.com":"news_publishers","politico.com":"news_publishers","huffpost.com":"news_publishers","buzzfeednews.com":"news_publishers"}
privacy.sanitize.useOldClearHistoryDialog false undefined
privacy.trackingprotection.content.annotation.enabled undefined false
privacy.trackingprotection.content.annotation.test_list_urls undefined
privacy.trackingprotection.content.protection.enabled undefined false
privacy.trackingprotection.content.protection.test_list_urls undefined
privacy.trackingprotection.content.testing undefined false
security.certerrors.felt-privacy-v1 false true
security.pdf_signature_verification.enable_test_trust_anchors undefined false
sidebar.revamp.round-content-area false true
toolkit.telemetry.enabled false true
urlclassifier.disallow_completions goog-downloadwhite-digest256,base-track-digest256,mozstd-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256 goog-downloadwhite-digest256,base-track-digest256,mozstd-trackwhite-digest256,content-track-digest256,mozplugin-block-digest256,mozplugin2-block-digest256,ads-track-digest256,social-track-digest256,analytics-track-digest256,base-fingerprinting-track-digest256,content-fingerprinting-track-digest256,base-cryptomining-track-digest256,content-cryptomining-track-digest256,fanboyannoyance-ads-digest256,fanboysocial-ads-digest256,easylist-ads-digest256,easyprivacy-ads-digest256,adguard-ads-digest256,social-tracking-protection-digest256,social-tracking-protection-facebook-digest256,social-tracking-protection-linkedin-digest256,social-tracking-protection-twitter-digest256,base-email-track-digest256,content-email-track-digest256,consent-manager-track-digest256,anti-fraud-track-digest256,harmful-addon-block-digest256
urlclassifier.features.harmfuladdon.blocklistTables harmfuladdon-block-digest256 harmful-addon-block-digest256
urlclassifier.features.harmfuladdon.entitylistTables harmfuladdon-entitylist-digest256
urlclassifier.globalCacheTable undefined goog-globalcache-proto
widget.wayland.force-move-to-rect undefined false