Does anyone know how to fix the issues with textures flickering when using Wine or Proton on Linux? I'm on Manjaro myself but it probably happens on other distro's too. On ProtonDB some people have the issue and some don't, but no one seems to have a solution to it. But it ruins the game for me and I don't want to play through it until I can get the issue fixed or a new Proton version fixes it. Of course a Linux port does exist but they obviously had to make it a Steam exclusive and leave us GOG users out of it.

Yep. Switch to playing the native port.
The same goes for Arch, Pop, Deb, Red, Blue, Hat, TrenchCoat whatever etc yadayada

I cannot try this today myself but did you try using DXVK?

Yeah, but what I was saying at the end of my post was that the Linux port only exists on Steam. I'm not re-buying the game on Steam when I just bought the whole trilogy at once on GOG recently I don't actually know how to change that. I just realised that I didn't mention in my post that I'm using Heroic Games Launcher. Supposedly it's pretty easy to change that in Heroic from what I've heard but I've never found the option anywhere.

all the tr@ckers in the world are at your disposal

What are you talking about?