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?
There are others as well but on Steam Deck the shaders are by far the most prominent of those. I’m not sure what the others are and how many of those are because the developer changed anything or if some are autogenerated by something on the Steam store back-end.