Firefox 109 release comes with the new Unified Extensions button in the toolbar making things cleaner when users have multiple extension installed. This feature also raises the extensions that run in the background allowing users to see the impact of the extensions on the current page or website.
This new version introduces web extensions using Manifest Version 3 support while still retaining support for Web extensions using version 2.
More Firefox 109 changes include: Spanish (es-ES, es-AR) builds have built-in dictionary for spellchecker, Support for scrollend events, Browser import support from Vivaldi, Opera GX, PIP now supports subtitles on HBO Max.
There are Linux-specific bug fixes that have been resolved. These include the YouTube seek bar not showing relevant info, Firefox crashing when used in Sway, Panels flickering under Wayland during animations, Screensaver is correctly inhibited during automatic scrolling, and HW accelerated formats are now listed in about:support.