This is difference between the default preference of Firefox 86.0 beta 6 and one of 85.0.1. This diff table is generated with my small script firefox-prefjs-surveyer.

Preference difference
PrefFirefox 85.0.1Firefox 86.0 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/ https://www.mozilla.org/%LOCALE%/firefox/beta
apz.gtk.touchpad_pinch.enabled undefined false
apz.popups.enabled false true
browser.contentblocking.cfr-milestone.milestones [1000, 5000, 10000, 25000, 50000, 100000, 500000] [1000, 5000, 10000, 25000, 50000, 100000, 250000, 314159, 500000, 750000, 1000000, 1250000, 1500000, 1750000, 2000000, 2250000, 2500000, 8675309]
browser.contentblocking.features.strict tp,tpPrivate,cookieBehavior4,cm,fp,stp,lvl2 tp,tpPrivate,cookieBehavior5,cm,fp,stp,lvl2
browser.contentblocking.state-partitioning.mvp.ui.enabled false true
browser.defaultbrowser.notificationbar false true
browser.download.hide_plugins_without_extensions true undefined
browser.download.show_plugins_in_list true undefined
browser.engagement.ctrlTab.has-used undefined false
browser.engagement.library-button.has-used undefined false
browser.newtabpage.activity-stream.discoverystream.spocs-endpoint-query undefined
browser.newtabpage.activity-stream.newNewtabExperience.colors undefined #0090ED,#FF4F5F,#2AC3A2,#FF7139,#A172FF,#FFA437,#FF2A8A
browser.newtabpage.activity-stream.telemetry.ut.events false true
browser.partnerlink.attributionURL https://topsites.services.mozilla.com/cid/amzn_2020_a1 https://topsites.services.mozilla.com/cid/
browser.partnerlink.campaign.topsites undefined amzn_2020_a1
browser.ssb.enabled false undefined
browser.tabs.remote.useOriginAttributesInRemoteType undefined false
browser.tabs.tooltipsShowPid false undefined
browser.tabs.tooltipsShowPidAndActiveness undefined false
browser.urlbar.update2 true undefined
browser.urlbar.update2.disableOneOffsHorizontalKeyNavigation true undefined
browser.urlbar.update2.oneOffsRefresh true undefined
browser.urlbar.update2.restyleBrowsingHistoryAsSearch true undefined
canvas.createConicGradient.enabled undefined false
devtools.command-button-errorcount.enabled undefined true
docshell.shistory.bfcache.allow_unload_listeners undefined false
docshell.shistory.bfcache.require_no_opener undefined false
dom.events.offset-in-svg-relative-to-svg-root undefined true
dom.input_events.beforeinput.enabled false true
dom.input_events.canSuspendInBCG.enabled undefined false
dom.popup_allowed_events change click dblclick auxclick mouseup pointerup notificationclick reset submit touchend contextmenu change click dblclick auxclick mousedown mouseup pointerdown pointerup notificationclick reset submit touchend contextmenu
dom.storage.next_gen false true
dom.window.content.untrusted.enabled true false
extensions.content_script_csp.enabled false undefined
extensions.content_script_csp.report_only true undefined
extensions.formautofill.supportedCountries US US,CA
extensions.getAddons.get.url https://services.addons.mozilla.org/api/v3/addons/search/?guid=%IDS%&lang=%LOCALE% https://services.addons.mozilla.org/api/v4/addons/search/?guid=%IDS%&lang=%LOCALE%
extensions.getAddons.langpacks.url https://services.addons.mozilla.org/api/v3/addons/language-tools/?app=firefox&type=language&appversion=%VERSION% https://services.addons.mozilla.org/api/v4/addons/language-tools/?app=firefox&type=language&appversion=%VERSION%
extensions.webcompat-reporter.enabled false true
extensions.webextensions.base-content-security-policy script-src 'self' https://* moz-extension: blob: filesystem: 'unsafe-eval' 'unsafe-inline'; object-src 'self' https://* moz-extension: blob: filesystem:; script-src 'self' https://* http://localhost:* http://127.0.0.1:* moz-extension: blob: filesystem: 'unsafe-eval' 'unsafe-inline'; object-src 'self' moz-extension: blob: filesystem:;
extensions.webextensions.base-content-security-policy.v3 undefined script-src 'self' http://localhost:* http://127.0.0.1:*; object-src 'self';
extensions.webextensions.tabhide.enabled true undefined
geo.provider.network.compare.url undefined https://www.googleapis.com/geolocation/v1/geolocate?key=%GOOGLE_LOCATION_SERVICE_API_KEY%
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.bundled-fonts.activate undefined -1
gfx.e10s.font-list.shared false true
gfx.font_rendering.fallback.async undefined true
gfx.webrender.debug.force-picture-invalidation undefined false
gfx.webrender.software.d3d11.upload-mode undefined 2
gfx.webrender.svg-images undefined false
image.avif.enabled false true
javascript.options.ion.full.threshold 100000 undefined
javascript.options.off_thread_parse_global true false
layout.css.autofill.enabled undefined true
layout.css.file-selector-button.enabled true undefined
layout.css.image-set.enabled undefined false
layout.css.moz-any-is-is.enabled true undefined
layout.css.moz-focus-outer.enabled false undefined
layout.css.text-decoration-skip-ink.enabled true undefined
layout.css.text-decoration-thickness.enabled true undefined
layout.css.text-justify.enabled true undefined
layout.css.text-underline-offset.enabled true undefined
layout.css.text-underline-position.enabled true undefined
layout.css.unknown-webkit-pseudo-element true undefined
layout.css.xul-tree-pseudos.content.enabled false undefined
layout.display-list.improve-fragmentation false true
layout.dynamic-reflow-roots.enabled false true
media.peerconnection.dtls.version.min 770 771
media.peerconnection.mtransport_process false true
media.videocontrols.keyboard-tab-to-all-controls undefined false
media.videocontrols.picture-in-picture.allow-multiple false true
network.cache.frecency_array_check_enabled undefined true
network.http.spdy.bug1556491 true undefined
network.http.spdy.bug1563695 true undefined
network.process.enabled false true
pdfjs.enableScripting undefined false
pdfjs.viewerCssTheme undefined 0
permissions.isolateBy.privateBrowsing false true
print.tab_modal.enabled false true
privacy.annotate_channels.strict_list.enabled false true
privacy.window.name.update.enabled false true
prompts.contentPromptSubDialog undefined true
prompts.tab_modal.enabled true undefined
remote.enabled undefined true
remote.force-local undefined true
security.disallow_non_local_systemprincipal_in_tests undefined false
security.intermediate_preloading_healer.enabled false true
security.osclientcerts.autoload false true
security.remote_settings.crlite_filters.enabled false true
security.ssl.errorReporting.automatic false undefined
security.ssl.errorReporting.enabled false undefined
security.ssl.errorReporting.url https://incoming.telemetry.mozilla.org/submit/sslreports/ undefined
services.sync.engine.bookmarks.validation.enabled undefined true
services.sync.engine.passwords.validation.enabled undefined true
svg.transform-box.enabled true undefined
toolkit.telemetry.enabled false true
webgl.disable-fail-if-major-performance-caveat false true
widget.remote-look-and-feel undefined true
widget.wayland_vsync.enabled false true