Switched to the beta version dx11_non-rt in the Steam game properties (under the Betas tab), then launched the game, went to Graphics settings, and changed the API from DX12 to DX11.

At first the game ran fine, but after a while some graphic glitches started showing up—textures stretching, breaking, etc. After switching to DX11 as suggested by another ProtonDB user (thank you VHXM), the game now runs perfectly with no graphical issues. Great experience overall!