This article shows the difference between the default preferences of Firefox 148.0 beta 3 and Firefox 147.0.1. The diff table below is generated using my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 148.0 beta 3Firefox 147.0.1
app.normandy.test-prefs.bool undefined false
app.normandy.test-prefs.integer undefined 0
app.normandy.test-prefs.string undefined
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 undefined Error
browser.aiwindow.endpoint undefined https://mlpa-prod-prod-mozilla.global.ssl.fastly.net/v1
browser.aiwindow.firstrun.autoAdvanceMS undefined 3000
browser.aiwindow.firstrun.modelChoice undefined
browser.aiwindow.memories undefined false
browser.aiwindow.memoriesLogLevel undefined Warn
browser.aiwindow.model undefined qwen3-235b-a22b-instruct-2507-maas
browser.aiwindow.preferences.enabled undefined false
browser.backup.backup-retry-limit 100 10
browser.crashReports.crashPull false true
browser.ipProtection.domainExclusions undefined
browser.ipProtection.domainInclusions undefined
browser.ipProtection.exceptionsMode all undefined
browser.newtabpage.activity-stream.discoverystream.personalization.enabled true false
browser.newtabpage.activity-stream.discoverystream.sections.cards.thumbsUpDown.enabled true undefined
browser.newtabpage.activity-stream.discoverystream.spocs.personalized true false
browser.newtabpage.activity-stream.discoverystream.thumbsUpDown.enabled false undefined
browser.newtabpage.activity-stream.discoverystream.thumbsUpDown.region-thumbs-config US US, CA
browser.newtabpage.activity-stream.externalComponents.enabled undefined true
browser.newtabpage.activity-stream.feeds.externalcomponentsfeed undefined true
browser.newtabpage.activity-stream.improvesearch.handoffToAwesomebar true undefined
browser.newtabpage.activity-stream.search.useHandoffComponent undefined true
browser.newtabpage.activity-stream.support.url https://support.mozilla.org/1/firefox/147.0.1/Linux/en-US/new-tab https://support.mozilla.org/1/firefox/148.0/Linux/en-US/new-tab
browser.newtabpage.activity-stream.telemetry.privatePing.enabled false true
browser.newtabpage.activity-stream.telemetry.privatePing.redactNewtabPing.enabled false true
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.newtabpage.activity-stream.widgets.system.weatherForecast.enabled undefined false
browser.newtabpage.activity-stream.widgets.weatherForecast.enabled undefined true
browser.newtabpage.activity-stream.widgets.weatherForecast.interaction undefined false
browser.sessionstore.log.appender.file.logOnSuccess false true
browser.sessionstore.loglevel Warn Debug
browser.tabs.groups.smart.suggestOtherTabsMethod NEAREST_NEIGHBOR LOGISTIC_REGRESSION
browser.tabs.remoteSVGIconDecoding undefined false
browser.translations.newSettingsUI.enable false undefined
dap.ohttp.hpke https://dap-09-3.api.divviup.org/ohttp-configs gAAgJSO22Y3HKzRSese15JtQVuuFfOIcTrZ56lQ5kDQwS0oABAABAAE
dom.about-blank-ckeditor-hack.enabled false true
dom.cookieStore.extra.enabled false undefined
dom.cookieStore.manager.enabled true undefined
dom.documentpip.enabled undefined false
dom.event.keypress.key.allow_lone_surrogate true false
dom.event.pointer.rawupdate.movement.enabled undefined true
dom.execCommand.paste.enabled undefined true
dom.forms.html_color_picker.enabled undefined false
dom.image-lazy-loading.root-margin.bottom 600.0 undefined
dom.image-lazy-loading.root-margin.bottom.percentage false undefined
dom.image-lazy-loading.root-margin.left 600.0 undefined
dom.image-lazy-loading.root-margin.left.percentage false undefined
dom.image-lazy-loading.root-margin.right 600.0 undefined
dom.image-lazy-loading.root-margin.right.percentage false undefined
dom.image-lazy-loading.root-margin.top 600.0 undefined
dom.image-lazy-loading.root-margin.top.percentage false undefined
dom.input.showPicker_datalist.enabled false true
dom.jsipc.send_typed false true
dom.keyboardevent.init_key_event.enabled_in_addons false true
dom.lazy-loading.margin.bottom undefined 600.0
dom.lazy-loading.margin.bottom.percentage undefined false
dom.lazy-loading.margin.is-scroll undefined true
dom.lazy-loading.margin.left undefined 600.0
dom.lazy-loading.margin.left.percentage undefined false
dom.lazy-loading.margin.right undefined 600.0
dom.lazy-loading.margin.right.percentage undefined false
dom.lazy-loading.margin.top undefined 600.0
dom.lazy-loading.margin.top.percentage undefined false
dom.location.ancestorOrigins.enabled undefined true
dom.security.sanitizer.enabled false true
dom.security.sanitizer.logging false undefined
dom.security.trusted_types.enabled false true
dom.security.unexpected_system_load_telemetry_enabled false true
dom.serializer.includeCommonAncestor.enabled undefined false
dom.viewTransitions.cross-document.enabled undefined false
dom.webgpu.enabled false true
dom.webgpu.service-workers.enabled false true
dom.workers.throttling.enabled false true
extensions.manifestV3.enabled true undefined
extensions.webcompat-reporter.enabled false true
gfx.color_management.hdr_video undefined true
gfx.color_management.hdr_video_assume_rec2020_uses_pq undefined true
gfx.webrender.dcomp-texture-overlay-win undefined false
gfx.webrender.overlay-hdr undefined true
gfx.webrender.precise-linear-gradients-swgl false true
javascript.options.asmjs true false
javascript.options.experimental.capture_oom_stack_trace undefined false
javascript.options.experimental.joint_iteration undefined true
javascript.options.experimental.legacy_regexp undefined false
javascript.options.wasm_branch_hinting false true
javascript.options.wasm_custom_page_sizes undefined false
layout.css.anchor-positioning.position-try-order.enabled false true
layout.css.basic-shape-shape.enabled false true
layout.css.letter-spacing.model 0 2
layout.dynamic-reflow-roots.enabled false true
mathml.legacy_mathvariant_attribute.disabled false true
mathml.mathspace_names.disabled false true
media.webrtc.simulcast.vp9.enabled false true
memory.phc.size_kb 1152 16384
network.auth.use_redirect_for_retries false true
network.dns.mru_to_tail undefined false
network.http.http2.push_priority_update false undefined
network.http.http3.retry_different_ip_family false true
network.http.retry_with_another_half_open false true
network.jar.record_failure_reason false true
network.predictor.doing-tests false undefined
network.predictor.enable-prefetch false undefined
network.predictor.enabled false undefined
network.predictor.max-resources-per-entry 100 undefined
network.predictor.max-uri-length 500 undefined
network.predictor.page-degradation.day 0 undefined
network.predictor.page-degradation.max 50 undefined
network.predictor.page-degradation.month 10 undefined
network.predictor.page-degradation.week 5 undefined
network.predictor.page-degradation.year 25 undefined
network.predictor.preconnect-min-confidence 90 undefined
network.predictor.prefetch-force-valid-for 10 undefined
network.predictor.prefetch-min-confidence 100 undefined
network.predictor.prefetch-rolling-load-count 10 undefined
network.predictor.preresolve-min-confidence 60 undefined
network.predictor.subresource-degradation.day 1 undefined
network.predictor.subresource-degradation.max 100 undefined
network.predictor.subresource-degradation.month 25 undefined
network.predictor.subresource-degradation.week 10 undefined
network.predictor.subresource-degradation.year 50 undefined
network.trr.async_connInfo false true
network.trr.confirmation_telemetry_enabled true undefined
network.trr.idle_timeout_for_http3_conn 30 400
nimbus.rollouts.enabled undefined true
places.semanticHistory.featureGate false true
privacy.webrtc.preview.testGumDelayMs undefined 0
security.certerrors.felt-privacy-v1 false true
security.disallow_non_local_systemprincipal_in_tests undefined false
security.ssl3.ecdhe_ecdsa_aes_128_sha true false
security.ssl3.ecdhe_ecdsa_aes_256_sha true false
services.sync.engine.bookmarks.validation.enabled undefined true
services.sync.engine.passwords.validation.enabled undefined true
services.sync.prefs.sync.nimbus.rollouts.enabled undefined true
toolkit.telemetry.enabled false true
ui.new-webcompat-reporter.send-more-info-link false true