This is difference between the default preference of Firefox 92.0 beta 5 and one of 91.0.1. This diff table is generated with my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 91.0.1Firefox 92.0 beta 5
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.aboutwelcome.protonDesign true undefined
browser.cache.offline.enable true false
browser.newtabpage.activity-stream.discoverystream.config {"api_key_pref":"extensions.pocket.oAuthConsumerKey","collapsible":true,"enabled":true,"show_spocs":false,"hardcoded_layout":true,"personalized":true,"layout_endpoint":"https://getpocket.cdn.mozilla.net/v3/newtab/layout?version=1&consumer_key=$apiKey&layout_variant=basic"} {"api_key_pref":"extensions.pocket.oAuthConsumerKey","collapsible":true,"enabled":true,"show_spocs":false,"hardcoded_layout":true,"layout_endpoint":"https://getpocket.cdn.mozilla.net/v3/newtab/layout?version=1&consumer_key=$apiKey&layout_variant=basic"}
browser.newtabpage.activity-stream.discoverystream.personalization.enabled undefined true
browser.newtabpage.activity-stream.discoverystream.personalization.version 2 undefined
browser.newtabpage.activity-stream.discoverystream.spoc-positions undefined 2,4,11,20
browser.newtabpage.activity-stream.discoverystream.sponsored-collections.enabled undefined false
browser.newtabpage.activity-stream.feeds.recommendationprovider undefined true
browser.newtabpage.activity-stream.feeds.recommendationproviderswitcher true undefined
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.topsites.contile.enabled false true
browser.urlbar.experimental.firefoxSuggestLabels.enabled false undefined
browser.urlbar.groupLabels.enabled undefined true
devtools.inspector.color-scheme-simulation.enabled true undefined
devtools.performance.recording.objdirs.remote [] undefined
devtools.responsive.metaViewport.enabled true undefined
dom.block_download_insecure false true
dom.event.dragexit.enabled undefined true
dom.events.coalesce.touchmove false true
dom.image-lazy-loading.root-margin.bottom 300.0 800.0
dom.image-lazy-loading.root-margin.left 300.0 800.0
dom.image-lazy-loading.root-margin.right 300.0 800.0
dom.image-lazy-loading.root-margin.top 300.0 800.0
dom.select_events.textcontrols.enabled false undefined
dom.select_events.textcontrols.selectionchange.enabled undefined true
dom.select_events.textcontrols.selectstart.enabled undefined false
dom.serviceWorkers.testing.persistTemporarilyInstalledAddons undefined false
dom.shadowdom.slot.assign.enabled undefined true
dom.storage.next_gen false true
dom.webcomponents.disabledFeatures.enabled undefined true
dom.window.content.untrusted.enabled true false
dom.window.sidebar.enabled true false
extensions.webcompat-reporter.enabled false true
extensions.webextPermissionPrompts true undefined
general.autoscroll.prevent_to_start.altKey undefined false
general.autoscroll.prevent_to_start.ctrlKey undefined false
general.autoscroll.prevent_to_start.metaKey undefined false
general.autoscroll.prevent_to_start.osKey undefined false
general.autoscroll.prevent_to_start.shiftKey undefined 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.basic_layer_manager.force_enabled undefined false
gfx.webrender.compositor.max_update_rects 0 1
gfx.webrender.fallback.basic true false
gfx.webrender.force-disabled false undefined
gfx.webrender.force-legacy-layers undefined false
image.avif.enabled false true
javascript.options.wasm_simd_wormhole undefined false
layout.css.accent-color.darkening-target-contrast-ratio undefined 6.0
layout.css.accent-color.enabled false true
layout.css.accent-color.min-contrast-ratio undefined 3.0
layout.css.clip-path-path.enabled true undefined
layout.css.color-scheme.enabled undefined false
layout.css.computed-style.throw-on-invalid-pseudo undefined false
layout.css.font-size-adjust.basis.enabled false true
layout.css.image-set.enabled true undefined
layout.css.prefixes.columns false undefined
layout.css.size-adjust.enabled false true
layout.css.system-ui.enabled undefined true
layout.dynamic-reflow-roots.enabled false true
marionette.log.level Info undefined
marionette.log.truncate true undefined
media.peerconnection.mtransport_process false true
network.cache.bug1708673 undefined true
network.cache.frecency_array_check_enabled false true
network.dns.upgrade_with_https_rr false true
network.dns.use_https_rr_as_altsvc false true
network.http.largeKeepaliveFactor undefined 10
network.http.referer.disallowCrossSiteRelaxingDefault undefined true
network.http.spdy.bug1563538 true undefined
network.jar.record_failure_reason false true
network.process.enabled false true
pdfjs.enableXfa false true
privacy.annotate_channels.strict_list.enabled false true
privacy.partition.network_state.ws_connection_queue undefined true
reader.pocket.ctaVersion undefined
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
services.sync.prefs.sync.privacy.fuzzyfox.clockgrainus false undefined
services.sync.prefs.sync.privacy.fuzzyfox.enabled false undefined
signon.usernameOnlyForm.enabled false true
toolkit.telemetry.enabled false true
webgl.enable-renderer-query undefined true
webgl.override-unmasked-renderer undefined
webgl.override-unmasked-vendor undefined
webgl.sanitize-unmasked-renderer undefined true
widget.wayland.multi-buffer-software-backend.enabled false true