Your system information

• Steam client version (build number or date): Steam Version: 1751405894
• Distribution (e.g. Ubuntu): Linux mint
• Opted into Steam client beta?: No
• Have you checked for system updates?: Yes
• Steam Logs: steam-logs.tar.gz
• GPU: AMD 6650

Please describe your issue in as much detail as possible:

I am using untypical 16:18 screen for work and games. (2560x2880 by LG). Some days ago, I noticed that proton games are confused and offers only pivoted resolutions like 1200:1920 instead of 1920:1200. When I manually set Proton 9.0.4, problem disappears. Tested on KCD and Planetcrafter. It feels that native linux games like XCOM2 are also confused into some degree. While vertical screen is great for work, many games benefits from horizontal one.

Steps for reproducing this issue:

1. Connect 2560x2880 screen
2. Start proton game
3. Try to set resolution
4. Resolution is pivoted
5. Switch to Proton 9.0.4
6. Check resolution
7. You can set normal resolution

KCD:

Planet crafter: