NTFS drive?

I don't think you can even have ubuntu installed on ntfs. I suppose maybe you mean there's people that have ntfs partitions mounted from which they run their steam games??? anyway it's normal ext4.

Then I have no idea. I have never seen this anywhere. Maybe enable proton logging for the game and check what it says.

Shaders?

i had issue with launching games in the past (with proton 7), when games didn't start if almost all ram was full, even it it was just io cache. try this before launching games, and see if it helps. this is non-destructive operation.

Dominions and Pathfinder don't run under Proton (if I understand it correctly) because they're Linux native. Thanks for the replies anyway I'll try sync.

b.t.w these games run normally, every time when run directly not through steam from their steam installation directory (e.g. via the terminal). It's clearly something wrong with steam.