SteamOS beta makes game resolution wonky or not fullscreen

[AlfianArdian]

Your system information

• Steam client version: 1723601482 , build date aug 14 8:51
• SteamOS version: 3.6.9 beta, steam deck LCD
• Opted into Steam client beta?: Yes
• Opted into SteamOS beta?: Yes
• Have you checked for updates in Settings > System?: Yes

Please describe your issue in as much detail as possible:

Describe what you expected should happen and what did happen. I've tried this repeatedly from 3.6.0 preview to 3.6.9 beta and different steam client including beta or not, i play lies of p as non-steam game the resolution on the game always not fullscreen and wonky, it keeps happening everytime and easily reproduced though i just realizing i can fix it by turning ON and OFF the disable frame limit every game launch, reverted back to 3.5.19 stable and i don't have this problem at all I have this problem too playing forza horizon 4 on my steam library when launching first time, fix it by turning ON and OFF disable frame limit but the problem doesn't happen again. I think it's steamos problem not proton, steam client beta, or anything else

Steps for reproducing this issue:

1. update to 3.6.9 beta from 3.5.19 stable
2. run non-steam game like lies of p on my case
3. the screen is not fullscreen like first picture
4. Turn on and off or off and on disable frame limit to fix it
5. exit the game, repeat, the problem still persists

[unclejack]

I've encountered the same issue with several games from Steam. The workaround for me has been to set the mode to "windowed fullscreen" or "borderless window". The frame limit and other display related settings from the SteamOS overlay don't make a difference.

[unclejack]

I can confirm that this happens with several games:

• on Bazzite in gaming mode on the Steam Deck
• on SteamOS on the plasma desktop
• on SteamOS in game mode

There seems to be some issue with reporting resolutions or setting the resolution properly. I was surprised to reproduce this outside of gamescope/SteamOS.

The theory that this is an issue specific to a game engine, to a game or to non-Steam games is also not valid. This issue manifests itself with several games with various game engines. Some games are able to start with the proper resolution. Any attempt to change v-sync settings, the graphics settings or frame rate limits from within the game leads to the same issue. I was able to get one game to work again with its default full screen setting after clearing the wine prefix via the game settings from the SteamOS game mode. Otherwise windowed full screen or borderless window are required to display the image properly on the screen. It's not something I've investigated further. I hope it helps someone who debugs the issue at some point.

[AlfianArdian]

for me it works as usual and no issues when on desktop mode after deleting proton/wine prefix like you said but problem still present on gaming mode also after deleting proton/wine prefix in-game resolution setting doesn't help