aka @rotopenguin@mastodon.social
I’m not sure how much influence you can really have there. Steam is supposed to have every dependency sorted out for you. A native linux game should have a fixed environment, it runs in a bit of a canned distro such as “Scout” (Debian 16.04 iirc).
If the Linux build is broken, you’re usually best off to change it to run Proton.
Quite a few drm-free game builds still come with “steamapi.dll”. It’s supposed to be neutered, but maybe it still saw dregs of your steam install and tried talking to steam anyways? It might just need a “steam_appid.txt” file (with just the appid # inside) to nicely ask it to back off. Or the game might go merrily along with removing the steam dlls.
ProtonTricks may be the app for your problem. It can run Winetricks specifically targeting the prefixes that Steam sets up for each individual game. Soo, (I do not have BG3) run Protontricks, pick the game, wait, find that Winetricks starts off at a really awkward point in its UI, pick add an application, cancel, find yourself at a better menu, choose “Install a Windows DLL or component”, and check off the appropriate dot net version.
When somebody tells you “fuck off, I don’t want your business”, believe them.