This is difference between the default preference of Firefox 96.0 beta 3 and one of 95.0. This diff table is generated with my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 95.0Firefox 96.0 beta 3
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/ https://www.mozilla.org/%LOCALE%/firefox/beta
browser.active_color.dark #FF9E9E #FF6666
browser.anchor_color.dark #9E9EFF #8C8CFF
browser.cache.offline.enable true false
browser.download.alwaysOpenPanel undefined true
browser.history.maxStateObjectSize 2097152 16777216
browser.low_commit_space_threshold_mb undefined 200
browser.low_commit_space_threshold_percent undefined 5
browser.newtabpage.activity-stream.asrouter.providers.messaging-experiments {"id":"messaging-experiments","enabled":true,"type":"remote-experiments","messageGroups":["cfr","moments-page","aboutwelcome","infobar","spotlight"],"updateCycleInMs":3600000} {"id":"messaging-experiments","enabled":true,"type":"remote-experiments","messageGroups":["cfr","aboutwelcome","infobar","spotlight","moments-page"],"updateCycleInMs":3600000}
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.snapshots.score.CurrentSession undefined 1
browser.snapshots.score.InNavigation undefined 3
browser.snapshots.score.IsOverlappingVisit undefined 3
browser.snapshots.score.IsUsedRemoved undefined -10
browser.snapshots.score.IsUserPersisted undefined 1
browser.snapshots.score.Visit undefined 1
browser.startup.upgradeDialog.enabled false true
browser.tabs.remote.serviceWorkerIsolationList undefined
browser.urlbar.merino.enabled false true
browser.visited_color.dark #D0ADF0 #FFADFF
devtools.command-button-paintflashing.enabled false undefined
devtools.contenttoolbox.webconsole.input.context false undefined
devtools.debugger.features.blackbox-lines undefined false
devtools.debugger.features.original-blackbox true undefined
dom.document.edit_command.contentReadOnly.enabled undefined true
dom.document.edit_command.decreasefontsize.enabled undefined false
dom.document.edit_command.gethtml.enabled undefined false
dom.document.edit_command.heading.enabled undefined false
dom.document.edit_command.increasefontsize.enabled undefined false
dom.document.edit_command.insertBrOnReturn.enabled undefined true
dom.document.edit_command.readonly.enabled undefined false
dom.image-lazy-loading.root-margin.bottom 300.0 500.0
dom.image-lazy-loading.root-margin.left 300.0 500.0
dom.image-lazy-loading.root-margin.right 300.0 500.0
dom.image-lazy-loading.root-margin.top 300.0 500.0
dom.maxHardwareConcurrency 16 128
dom.weblocks.enabled false true
dom.window.content.untrusted.enabled true false
dom.window.sidebar.enabled true false
editor.create_element_transaction.enabled undefined false
editor.hr_element.allow_to_delete_from_following_line false true
extensions.webcompat-reporter.enabled false true
fission.highValue.login.expiration undefined 2592000
fission.highValue.login.monitor undefined false
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 undefined false
gfx.canvas.accelerated.cache-items undefined 1024
gfx.canvas.accelerated.cache-size undefined 128
gfx.canvas.accelerated.max-size undefined 0
gfx.canvas.accelerated.max-surface-size undefined 5280
gfx.canvas.accelerated.min-size undefined 128
gfx.canvas.accelerated.shared-page-size undefined 1024
gfx.webrender.batched-upload-threshold undefined 65536
gfx.webrender.debug.tile-cache-logging false undefined
gfx.webrender.debug.window-visibility undefined false
javascript.options.mem.incremental_weakmap undefined true
javascript.options.wasm_simd_wormhole undefined false
layout.css.autofill.background true undefined
layout.css.autofill.enabled true undefined
layout.css.color-scheme.enabled false true
layout.css.computed-style.dont-resolve-image-local-refs undefined true
layout.css.computed-style.shorthands undefined true
layout.css.computed-style.styles-outside-flat-tree undefined true
layout.css.moz-locale-dir.content.enabled undefined false
layout.css.moz-lwtheme.content.enabled undefined false
layout.css.moz-submit-invalid.enabled false undefined
layout.css.scroll-anchoring.reselect-if-suboptimal undefined true
layout.css.scroll-behavior.enabled true undefined
layout.css.scrollbar-gutter.enabled undefined false
layout.dynamic-reflow-roots.enabled false true
layout.forms.input-type-show-password-button.enabled undefined false
layout.outline.include-overflow undefined false
media.getusermedia.aec_extended_filter true undefined
media.getusermedia.aecm_output_routing 3 undefined
media.getusermedia.agc2_forced undefined true
media.getusermedia.noise 1 2
media.getusermedia.residual_echo_enabled undefined false
media.getusermedia.transient_enabled undefined true
media.gmp-manager.checkContentSignature undefined true
media.peerconnection.mtransport_process false true
media.peerconnection.mute_on_bye_or_timeout false undefined
media.rdd-ffmpeg.enabled false true
midi.testing undefined false
network.cache.frecency_array_check_enabled false true
network.cookie.sameSite.laxByDefault false true
network.cookie.sameSite.noneRequiresSecure false true
network.cookie.sameSite.schemeful false true
network.http.http3.priorization undefined true
network.http.http3.send_background_tabs_depriorization undefined false
network.http.referer.disallowCrossSiteRelaxingDefault false true
network.jar.record_failure_reason false true
network.predictor.enable-prefetch false true
network.process.enabled false true
network.proxy.detect_system_proxy_changes undefined false
network.trr.async_connInfo undefined false
network.trr.blocklist_cleanup_done false undefined
network.trr.temp_blocklist undefined true
network.url.max-length 0 33554432
nglayout.debug.paint_flashing false undefined
nglayout.debug.paint_flashing_chrome false undefined
print.print_unwriteable_margin_bottom -1 undefined
print.print_unwriteable_margin_left -1 undefined
print.print_unwriteable_margin_right -1 undefined
print.print_unwriteable_margin_top -1 undefined
privacy.annotate_channels.strict_list.enabled false true
privacy.partition.serviceWorkers undefined false
security.disallow_non_local_systemprincipal_in_tests undefined false
security.intermediate_preloading_healer.enabled false true
security.remote_settings.crlite_filters.enabled false true
services.sync.engine.bookmarks.validation.enabled undefined true
services.sync.engine.passwords.validation.enabled undefined true
toolkit.telemetry.enabled false true
ui.-moz-autofill-background undefined rgba(255, 249, 145, .5)
ui.key.textcontrol.prefer_native_key_bindings_over_builtin_shortcut_key_definitions undefined false
ui.key.use_select_all_in_single_line_editor undefined false
ui.textSelectAttentionBackground undefined #38d878
ui.textSelectAttentionForeground undefined #ffffff
ui.textSelectBackgroundAttention #38d878 undefined
ui.textSelectBackgroundDisabled #b0b0b0 undefined
ui.textSelectDisabledBackground undefined #b0b0b0
webgl.out-of-process.worker undefined true
webgl.threadsafe-gl.force-disabled undefined false
webgl.threadsafe-gl.force-enabled undefined false
widget.non-native-theme.scrollbar.size 12 undefined
widget.non-native-theme.scrollbar.size.override undefined 0
widget.non-native-theme.scrollbar.style undefined 0