Are you trying to play the Steam version outside of Steam?

Are you trying to play the Steam version outside of Steam?

Yes

Definitely not a vkd3d-proton problem then and you'd need to use something like a steamapi emulator to make this work. This is not the place to ask for support with this.

Yes

Well there is your issue then.

Edit: To expand a bit. Steam games will expect to be run from Steam itself and will often refuse to launch on the side either as part of drm or because they need to interact with a Steam service in some way.