

It is possible that you are running the windows version. You can find out in properties of the game. If the ‘force compatability tool’ is checked, under compatability, it will download the windowns version and run it through compatability layers. Otherwise you might have just seen the dialog about precompiling shaders.
Worth noting that sometimes developers make a linux version of their game, but neglects maintaining it. In those cases it is preferable to just run the windows version with comp layers. I think the linux native valheim version is alright though. Good devs.
Ctrl+F3 disables the hud.