With Firefox previously being installed with the OS, it would only update with the OS updates and Valve were lagging behind on it (a lot). Now it's a Flatpak from Flathub, so it will get installed and updated via the Discover app so you will be able to sort updates yourself in desktop mode.
They also added a "VGUI2 Classic" desktop theme, made it so network connections made and edited in desktop mode will now be system wide to work properly in Gaming Mode, initial IBus IME input support on desktop mode for Chinese / Japanese / Korean keyboards, and fixed up Xbox login window for Flight Simulator and Halo Infinite not rendering certain characters properly.
One that really catches the eye though is the note that there's been updates to "controller firmware utilities to support future controller hardware revisions". Before getting overly excited about a Steam Controller 2 though, it's most likely aimed towards adjustments to manufacturing of the Steam Deck as we already know it's had a few adjustments since the initial first batch. That said, I would love a Steam Controller 2, please Valve.
Update — not too long after, Valve also released a Steam Deck Client Beta with these changes:
- Added favorite and popular guides to the Steam Overlay for easy access
- Added notification when Steam Deck temperature goes outside the safe operating range
- Achievement progress notifications (ie. You've collected 5/100 berries) will no longer play sounds
- Resized virtual keyboard in Desktop mode to the appropriate dimensions
- Fixed some performance problems for users with many screenshots
- Fixed some navigation issues on an app's Achievements page
- Fixed some touch styling issues with the virtual keyboard
- Fixed sound playing for achievement progress notifications
- Fixed overlay menu issues with games that do not have achievements