maybe I can help https://www.reddit.com/r/SteamDeck/comments/1868qyv/steam_deck_oled_hdr_games_guide

maybe I can help https://www.reddit.com/r/SteamDeck/comments/1868qyv/steam_deck_oled_hdr_games_guide

Unfortunately, I don’t have any of these games in my Steam library, so I can’t test some of the settings.

Run as a Non-Steam game directly on Steam.

For all newer games I use Proton Experimental Bleeding-EDGE.

I had the same problem. When I deleted all the configuration files and everything was working fine.
I investigated what could be the problem with my optimal performance settings for SD and I think I found the cause.
See if you have bGroupRenderAllShadows=1 in StarfieldCustom.ini. This item with the value 1 causes the shadows to flash in the character menu and after a while it freezes and restarts Steam on SD. Just set it to 0 or delete it. It helped me.