Guild Wars 2 does not support D3D11.

For other games, select it in the game options if possible. Which DirectX version is used isn't decided by DXVK at all.

What exactly did you really do? You cannot run the game with DX11 because the game doesn't support it. It's a D3D9 game.

For using D9VK I once created a folder named "d9vk-2c081e03" (or whatever the current version of d9vk back then was named like) in "~/.local/share/lutris/runtime/dxvk" where I put the decompressed d9vk libraries from your build. In Lutris' options I activated "Enable DXVK" and set "DXVK version" to "d9vk-2c081e03" for making it use the D9VK libraries. I also enabled the HUD for showing the version and could verify that it was actually using the current d9vk.

And when I didn't need the faster fps but wanted the other optics I selected "DXVK Version" as "1.5.1" from the given defaults list for making it use the DXVK library instead. The game ran using both settings, but everytime I toggles between both there was a distinctive graphical difference.

You were using wined3d then, which is wine's default OpenGL backend.

Thank you, this explains how it would run without using D9VK.

It seems that I was using Lutris wrong then, didn't I? I would expect Wine to have loaded the dxvk libraries and output an error instead, if a game this game couldn't run with dxvk selected. Why did it not do this and run it using wined3d instead?
Could you please shortly explain this behaviour for my understanding?
Is there an automatic fallback to wined3d if the selected API is not compatible?

Basically, when you set lutris / proton to enable dxvk, they just make sure that DirectX9-DirectX11 is available for games to use in the version provided by dxvk instead of the default wine implementation. So dxvk replaces the default wined3d implementation if you enable that option. It is entirely up to the game whether or not the game uses any of those APIs. You could probably launch the windows calculator through Lutris and enable dxvk, but the calculator simply won't use any DirectX version at all (I guess). So libraries are only loaded on demand.

When you set Lutris to enable DirectX11 only, then all the other DirectX versions still use the default wined3d implementation, because they were not replaced to use dxvk. So in that case, DirectX9 games simply use wined3d.

Thank you very much!
I learned a bit more :)