


I ran the game using Proton 9.0-3 and it worked great.

Back buttons for changing weapons
In some rare areas the framerate dips
Freeze after a couple of checkpoint loads in each run. Freeze before the final cutscene

Final credits video crashed the game. after the final fight the game shows static noise screen that you need to skip fast or the game will crash.
no tinkring needed, unless you want to limit TDB. final credits is broken and you need to skip or repeat the mission.
Changed Proton version to 5.13-6 before final mission and removed compatdata for Rustler.
On default Proton or Proton-GE after beating final mission, screen goes dark and it exits the game.
You can play on default Proton or Proton-GE without any issues but for the last mission, change the version to 5.13-6 and clear compatdata. One user claimed that he finished whole game on 5.13-6 without any issues: https://steamcommunity.com/app/844260/discussions/0/3115898713372567768/?ctp=12
Graphical glitches on video cutscenes
When changing the resolution you need to restart the game, otherwise it doesn't adjust automatically.
If you use "continue" option instead of loading the save directly, it looks like two game instances are running, making it unplayable and definitely not "Steam Deck verified" status worthy.
Crashes every 2h
All of the mentioned in particular point's, amount of bugs is significant and not worthy "Steam Deck verified" status at this stage.