You’ll want to change the compatibility for Black Mesa.
In your Steam Library go to Black Mesa > hit the gear icon > select ‘Properties…’ > Compatibility > and check “Force the use of a specific Steam Play compatibility tool”
Either select Proton Experimental or Proton 8.0-4 (latest ver.)
After that you’re solid. I had no problems running the game on ‘High’ for the Earth levels. Performance took a hit from Xen to the end though, so may want to drop it down to ‘Medium’ after that.
Has anyone gotten pushback from Steam Support regarding their RMA request for dead pixels?
I submitted my ticket with pictures. They finally got back to me 2 days later and asked me to continue using it for a few weeks and if it doesn’t magically get fixed (It’s a dead pixel, not a stuck pixel) then they’ll take my Steam Deck in to get fixed.