This is difference between the default preference of Firefox 108.0 beta 6 and one of 107.0. This diff table is generated with my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 107.0Firefox 108.0 beta 6
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-browser&utm_campaign=whatsnew https://www.mozilla.org/%LOCALE%/firefox/%VERSION%beta/releasenotes/?utm_source=firefox-browser&utm_medium=firefox-browser&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
apz.scrollend-event.content.delay_ms undefined 100
browser.cache.offline.enable true false
browser.cache.shutdown_io_time_between_cancellations_ms undefined 5
browser.migrate.brave.enabled undefined true
browser.migrate.canary.enabled undefined true
browser.migrate.chrome-beta.enabled undefined true
browser.migrate.chrome-dev.enabled undefined true
browser.migrate.chrome.enabled undefined true
browser.migrate.chromium-360se.enabled undefined true
browser.migrate.chromium-edge-beta.enabled undefined true
browser.migrate.chromium-edge.enabled undefined true
browser.migrate.chromium.enabled undefined true
browser.migrate.edge.enabled undefined true
browser.migrate.firefox.enabled undefined true
browser.migrate.ie.enabled undefined true
browser.migrate.opera.enabled undefined false
browser.migrate.safari.enabled undefined true
browser.newtabpage.activity-stream.discoverystream.spocTopsitesAdTypes undefined
browser.newtabpage.activity-stream.discoverystream.spocTopsitesZoneIds undefined
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.pdfjs.feature-tour {"message":"PDF_JS_FEATURE_TOUR","screen":"","complete":false} {"screen":"FEATURE_CALLOUT_1","complete":false}
browser.urlbar.quickactions.enabled undefined true
browser.urlbar.quickactions.showInZeroPrefix undefined true
browser.urlbar.quickactions.showPrefs undefined true
browser.urlbar.shortcuts.quickactions undefined true
browser.urlbar.showSearchTerms false undefined
browser.urlbar.showSearchTerms.enabled undefined true
browser.urlbar.showSearchTerms.featureGate undefined false
browser.urlbar.suggest.quickactions undefined true
browser.urlbar.suggest.weather undefined true
browser.urlbar.weather.featureGate undefined false
clipboard.plainTextOnly false undefined
cookiebanners.bannerClicking.enabled false true
cookiebanners.ui.desktop.enabled undefined false
devtools.styleeditor.atRulesSidebarWidth undefined 238
devtools.styleeditor.mediaSidebarWidth 238 undefined
devtools.styleeditor.showAtRulesSidebar undefined true
devtools.styleeditor.showMediaSidebar true undefined
docshell.shistory.bfcache.ship_allow_beforeunload_listeners false true
dom.document.edit_command.contentReadOnly.enabled true false
dom.document.edit_command.insertBrOnReturn.enabled true false
dom.events.dataTransfer.mozFile.enabled undefined false
dom.fs.main_thread_writable_file_stream undefined false
dom.importMaps.enabled false true
dom.input_event_queue.duration.max undefined 8
dom.input_events.strict_input_vsync_alignment true undefined
dom.mozCurrentTransform.enabled false undefined
dom.origin-trials.offscreen-canvas.state 0 undefined
dom.picture_source_dimension_attributes.enabled false true
dom.security.credentialmanagement.identity.select_first_in_ui_lists undefined false
dom.sitepermsaddon-provider.enabled false true
dom.sitepermsaddon-provider.separatedBlocklistedDomains undefined shopee.co.th
dom.webidl.crosscontext_hasinstance.enabled true false
dom.webmidi.enabled false true
editor.word_select.delete_space_after_doubleclick_selection undefined false
extensions.InstallTrigger.enabled true false
extensions.manifestV3.enabled false true
extensions.openPopupWithoutUserGesture.enabled undefined false
extensions.webcompat-reporter.enabled false true
geo.provider.network.url https://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_LOCATION_SERVICE_API_KEY% https://location.services.mozilla.com/v1/geolocate?key=%MOZILLA_API_KEY%
gfx.canvas.accelerated.gpu-path-size undefined 4
gfx.color_management.enablev4 false true
gfx.display.max-frame-rate undefined 0
gfx.offscreencanvas.domain-allowlist *.zoom.us,zoom.us undefined
gfx.offscreencanvas.domain-enabled true undefined
html5.inert.enabled false true
input_event_queue.count_for_prediction 9 undefined
input_event_queue.default_duration_per_event 1 undefined
input_event_queue.duration.max 8 undefined
input_event_queue.duration.min 1 undefined
javascript.options.experimental.class_static_blocks true undefined
javascript.options.experimental.ergonomic_brand_checks true undefined
javascript.options.experimental.private_fields true undefined
javascript.options.experimental.private_methods true undefined
javascript.options.experimental.top_level_await true undefined
layout.css.font-variant-emoji.enabled undefined false
layout.css.round.enabled undefined false
layout.css.trig.enabled false true
layout.dynamic-reflow-roots.enabled false true
media.seamless-looping-video undefined false
media.utility-process.max-crashes undefined 2
media.webrtc.platformencoder.sw_mft false true
network.cache.frecency_array_check_enabled false true
network.cookie.sameSite.laxByDefault false true
network.cookie.sameSite.noneRequiresSecure false true
network.jar.record_failure_reason false true
network.predictor.enable-prefetch false true
network.url.strip-data-url-whitespace undefined false
nimbus.qa.pref-1 undefined default
nimbus.qa.pref-2 undefined default
privacy.annotate_channels.strict_list.enabled false true
security.block_fileuri_script_with_wrong_mime false true
security.csp.script-src-attr-elem.enabled false true
security.csp.style-src-attr-elem.enabled false true
security.csp.unsafe-hashes.enabled undefined false
security.disallow_non_local_systemprincipal_in_tests undefined false
security.remote_settings.crlite_filters.enabled false true
security.sandbox.gpu.level undefined 0
services.sync.engine.bookmarks.validation.enabled undefined true
services.sync.engine.passwords.validation.enabled undefined true
toolkit.background_tasks.remove_directory.testing.sleep_ms undefined 0
toolkit.telemetry.dap.logLevel undefined Warn
toolkit.telemetry.dap_enabled undefined false
toolkit.telemetry.dap_helper undefined https://helper1.dap.cloudflareresearch.com/v01
toolkit.telemetry.dap_helper_owner undefined Cloudflare
toolkit.telemetry.dap_leader undefined https://interop-00.api.divviup.org
toolkit.telemetry.dap_leader_owner undefined ISRG
toolkit.telemetry.enabled false true
webchannel.allowObject.urlWhitelist https://content.cdn.mozilla.net https://support.mozilla.org https://install.mozilla.org https://content.cdn.mozilla.net https://install.mozilla.org
webgl.out-of-process.async-present false true
xul.panel-animations.enabled false undefined