Often when I launch a game through Steam that “processing Vulkan shaders” window appears and loads for a couple minutes. Sometimes it takes no time, sometimes it takes several minutes. But then, for larger games like Dune Awakening or Outer Worlds 2, the game needs to sit and process shaders for another couple minutes anyway. But for some games, like Enshrouded, I can skip the Vulkan processing with no problems in the game (I do that because the Vulkan processing doesn’t go anywhere). So what is that Vulkan processing for?
Steam Deck usually has precomputed shaders as well, so it’s unclear why you’re having that problem on Steam Deck, unless you are running an unusual os. I suppose they could be less mainstream games, too.
Maybe if you are using a beta of proton or similar that could case it too.
I, for one, enjoy continuing to run every single weird kind of windows program through Proton Expirimental, on my Deck, running on Bazzite.
I may have escaped GlAdOS, but I’ll be damned if I ever stop testing.