ToDo: diffs FF145-FF146

[Thorin-Oakenpants]

FF146 release date: Dec. 9th 2025

FF146 release notes
FF146 for developers
FF146 security advisories

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105 diffs (41 new, 39 gone, 25 different)

new in 146.0:

pref("browser.backup.tab-flush-timeout", 5000);
pref("browser.ipProtection.added", false);
pref("browser.ipProtection.autoStartEnabled", false);
pref("browser.ipProtection.autoStartPrivateEnabled", false);
pref("browser.ipProtection.domainInclusions", "");
pref("browser.ipProtection.features.autoStart", false);
pref("browser.ipProtection.features.siteExceptions", false);
pref("browser.ipProtection.panelOpenCount", 0);
pref("browser.ml.linkPreview.supportedLocales", "en");
pref("browser.newtabpage.activity-stream.discoverystream.attribution.enabled", false);
pref("browser.newtabpage.activity-stream.feeds.newtabattributionfeed", true);
pref("browser.search.widget.new", false);
pref("browser.tabs.dragDrop.multiselectStacking", false);
pref("browser.tabs.notes.enabled", false);
pref("browser.tabs.splitView.enabled", false);
pref("browser.theme.forced-colors-override.enabled", true);
pref("browser.urlbar.flightStatus.featureGate", false);
pref("browser.urlbar.quicksuggest.online.available", false);
pref("browser.urlbar.sports.featureGate", false);
pref("browser.urlbar.suggest.quicksuggest.all", false);
pref("browser.urlbar.suggest.sports", true);
pref("devtools.selfxss.count", 0);
pref("devtools.toolbox.selectedTool", "inspector");
pref("dom.input.showPicker_datalist.enabled", false);
pref("gfx.canvas.accelerated.max-snapshot-pbo-memory", 67108864);
pref("gfx.webrender.debug.external-composite-borders", false);
pref("layers.gpu-process.launch-in-background", true);
pref("layout.css.contrast-color.enabled", true);
pref("layout.css.custom-media.enabled", false);
pref("layout.css.text-decoration-inset.enabled", true);
pref("network.cache.purge_disable", false);
pref("network.cache.suspended_writer_delay_ms", 5000);
pref("network.lna.benchmarking-is-local", false);
pref("network.lna.etp.enabled", false);
pref("network.lna.local-network-to-localhost.skip-checks", true);
pref("network.lna.skip-domains", "");
pref("network.lna.websocket.enabled", false);
pref("security.qwacs.enable_test_trust_anchors", false);
pref("security.restrict_to_adults.always", false);
pref("security.restrict_to_adults.respect_platform", false);
pref("termsofuse.firstAcceptedDate", 0);

removed, renamed or hidden in 146.0:

pref("browser.menu.showCharacterEncoding", false);
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.enabled", false);
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.fakespot.ctaCopy", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.fakespot.ctaUrl", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.fakespot.defaultCategoryTitle", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.fakespot.enabled", true);
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.fakespot.footerCopy", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.feeds", "need_to_know, fakespot");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.listFeedTitle", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.locale-content-config", "en-US,en-GB,en-CA,de");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.region-content-config", "");
pref("browser.newtabpage.activity-stream.discoverystream.contextualContent.selectedFeed", "need_to_know");
pref("browser.newtabpage.activity-stream.system.showSponsoredCheckboxes", true);
pref("browser.preferences.experimental", true);
pref("browser.urlbar.update2.engineAliasRefresh", true);
pref("devtools.inspector.inactive.css.enabled", true);
pref("dom.events.script_execute.enabled", false);
pref("dom.workers.importScripts.enforceStrictMimeType", true);
pref("font.language.group", "x-western");
pref("font.size.inflation.disabledInMasterProcess", false);
pref("gfx.canvas.remote", false);
pref("gfx.canvas.remote.allow-in-parent", false);
pref("gfx.canvas.remote.worker-threads", 0);
pref("gfx.direct2d.disabled", true);
pref("gfx.direct2d.force-enabled", false);
pref("gfx.direct2d.target-independent-rasterization.disabled", false);
pref("intl.ellipsis", "…");
pref("intl.menuitems.alwaysappendaccesskeys", "");
pref("intl.menuitems.insertseparatorbeforeaccesskeys", true);
pref("javascript.options.experimental.json_parse_with_source", true);
pref("javascript.options.experimental.regexp_duplicate_named_groups", true);
pref("javascript.options.experimental.regexp_modifiers", true);
pref("layers.gpu-process.allow-software", true);
pref("layout.css.text-decoration-trim.enabled", false);
pref("mathml.centered_operators.disabled", true);
pref("mathml.top_bottom_spacing_for_stretchy_operators.disabled", true);
pref("mathml.unknown_mrow.enabled", true);
pref("privacy.query_stripping.strip_on_share.canDisable", true);
pref("services.sync.prefs.sync.browser.discovery.enabled", true);

changed in 146.0:

pref("browser.contentblocking.features.strict", "tp,tpPrivate,cookieBehavior5,cookieBehaviorPBM5,cryptoTP,fp,stp,emailTP,emailTPPrivate,-consentmanagerSkip,-consentmanagerSkipPrivate,lvl2,rp,rpTop,ocsp,qps,qpsPBM,fpp,fppPrivate,btp,lna"); // tp,tpPrivate,cookieBehavior5,cookieBehaviorPBM5,cryptoTP,fp,stp,emailTP,emailTPPrivate,-consentmanagerSkip,-consentmanagerSkipPrivate,lvl2,rp,rpTop,ocsp,qps,qpsPBM,fpp,fppPrivate,btp
pref("browser.migrate.ie.enabled", false); // true
pref("browser.ml.linkPreview.enabled", true); // false
pref("browser.ml.linkPreview.noKeyPointsRegions", ""); // AD,AT,BE,BG,CH,CY,CZ,DE,DK,EE,ES,FI,FR,GR,HR,HU,IE,IS,IT,LI,LT,LU,LV,MT,NL,NO,PL,PT,RO,SE,SI,SK
pref("browser.newtabpage.activity-stream.discoverystream.sections.region-content-config", "US"); // 
pref("browser.newtabpage.activity-stream.support.url", "https://support.mozilla.org/1/firefox/146.0/Linux/en-US/new-tab"); // https://support.mozilla.org/1/firefox/145.0/Linux/en-US/new-tab
pref("browser.newtabpage.activity-stream.weather.optInDisplayed", true); // false
pref("browser.newtabpage.activity-stream.weather.staticData.enabled", true); // false
pref("browser.safebrowsing.provider.google5.lists", "goog-badbinurl-proto,goog-downloadwhite-proto,goog-phish-proto,googpub-phish-proto,goog-malware-proto,goog-unwanted-proto,goog-harmful-proto"); // goog-phish-proto,googpub-phish-proto,goog-malware-proto,goog-unwanted-proto,goog-harmful-proto
pref("browser.urlbar.quicksuggest.settingsUi", 1); // 0
pref("gfx.webrender.precise-conic-gradients", true); // false
pref("gfx.webrender.precise-radial-gradients-swgl", false); // true
pref("intl.accept_languages", "und"); // en-US, en
pref("javascript.options.experimental.symbols_as_weakmap_keys", true); // false
pref("javascript.options.wasm_relaxed_simd", true); // false
pref("layers.gpu-process.startup_timeout_ms", 10000); // 5000
pref("layout.css.at-scope.enabled", true); // false
pref("layout.css.webkit-fill-available.enabled", true); // false
pref("mathml.math_shift.enabled", true); // false
pref("mathml.rtl_operator_mirroring.enabled", true); // false
pref("media.devices.enumerate.legacy.allowlist", "slack.com,*.slack.com,riverside.fm,*.riverside.fm"); // slack.com,*.slack.com
pref("media.peerconnection.sctp.use_dcsctp", true); // false
pref("media.webrtc.send_mlkem_keyshare", true); // false
pref("network.dns.resolver_shutdown_timeout_ms", 5000); // 2000
pref("widget.wayland.fractional-scale.enabled", true); // false

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ignore

click me for details

==NEW

==REMOVED, RENAMED or HIDDEN

==CHANGED

[Jee-Hex]

some hidden prefs

• browser.newtabpage.shouldInitialize
  Bug 1944147 - Option to turn off newtab for automated tests and other automation.

FYI this is a 146-only hidden pref.