Firefox Nightly
Release Notes

Firefox now prompts Windows users to install the Microsoft AV1 Extension to enable hardware decoding support from about:support if not already installed.

Firefox now supports Voice Control commands on macOS systems.

Firefox now allows you to force-underline links in websites. This is useful for people with achromatopsia for example.

On Linux, Firefox now defaults to the Wayland compositor when available instead of XWayland. This brings support for touchpad & touchscreen gestures, swipe-to-nav, per-monitor DPI settings, better graphics performance, and more.

Note that due to Wayland protocol limitations, Picture-in-Picture windows require an extra user interaction (generally right-click on the window) or a shell / desktop-environment tweak. See bug 1621261 for related discussion and tracking, this post for a KDE configuration, and this extension for GNOME.

Starting with Firefox 120, ULPFE/RED is now on by default for video in Nightly builds. This provides additional protection against packet loss for video during WebRTC calls.

The CSS text-indent property now supports the hanging and each-line keywords, offering more convenient paragraph layout for styles such as bibliographies, poetry, etc.

Firefox now supports text-wrap: balance, which can improve the appearance of short multi-line text blocks such as long headings or captions by harmonizing the line lengths.

Lazy loading iframes are now supported (<iframe loading=lazy>). Lazy loading iframes are only loaded when visible, so non-critical iframes can load later when needed to speed up initial page loads, reduce initial network usage, etc.

The :has() selector is now supported. This allows authors to match elements that has, or "anchors", at least one element matching its relative selector.

Support has been added for tail call elimination in WebAssembly language to improve support for functional languages.