I've heard that it works fairly well on Proton already. In fact, perhaps even better than it does on Windows in some regards as a result of Valve having implemented some mitigations for things the engine does incorrectly in Proton. (Thanks to a desire to have the game work properly on the Steam Deck)
I haven't tried yet, though, as I'm playing my way through the Dark Souls series proper before giving Elden Ring a try.
Proton uses Vulkan to replace DirectX and Elden Ring's handling of DirectX isn't optimal, or something along those lines. The end result is the game running better on Linux because it coincidentally circumvents those issues.
I haven't tried yet, though, as I'm playing my way through the Dark Souls series proper before giving Elden Ring a try.