Recently Valve put up a Beta for Steam desktop and Steam Deck, which unfortunately came with a huge bug that people found but a new release fixes it and adds some more fixes too.
The bug was quite a big woops, that ended up causing people on Linux and Steam Deck to be unable to open anything after Steam had been open for a short time.
- Fixed regression causing "Maximum number of clients reached" issue
- Fixed Patch Notes button on Downloads page entries
New Big Picture Mode
- Allow onscreen keyboard to be activated while in New Big Picture Mode and Steam window is not focused
- Fixed some issues where onscreen keyboard and controller configurator windows could not be reactivated after closing
- Fixed issue opting in to some game beta branches
- Fixed issue w/ Joystick Deadzone visualization not updating
It seems they actually realised at least for the update before this, that they had copy / pasted a feature from desktop to Steam Deck not actually available on Steam Deck. The feature being the new full / partial controller icon being added on game hover in your library, as they actually went back and removed it from the changelog. The one before that still lists some controller options not actually available on Steam Deck though — would be nice if these things were checked fully before going out in their official changelogs to not confuse users.