Quoting: CybolicIt's actually been in the stable client for months. Before now, it just had to be launched with two arguments instead of the one. I was running it for a couple of months earlier in the year with gamescope (behaves better that way) using the following command:
gamescope -W 3440 -H 1440 --steam -f -- /usr/bin/steam-runtime -steamos -gamepadui
Back then I got annoyed with the client trying to control the system - things like shutting down the OS on exit or wanting to restart the system, which makes perfect sense on Steam Deck, but not on desktop - so I went back to the standard client.

EDIT: I assume the new stuff is that it works better without gamescope - first step to becoming a proper desktop client.