I can reproduce it on any level, even stock ones so it's not specific to any level and it most likely has something to do with my hardware (though Csonicgo was also capable of reproducing the same bug, though the aformentioned textures literally just disappeared for him, instead of warping).
Here's how I can successfully reproduce it on Doom E1M1, but the steps have to be followed EXACTLY in this order:
- Switch to 800x600 in fullscreen mode, enable "shaders for colormaps", and restart GZDoom so that it's the default resolution and setting.
- Walk over so you see the sargeants and the armor to the left room.
- (optional) Freeze the game so the sprites stay where they are, this will let you pick up the effect if it occurs.
- Give yourself the infrared goggles, or for an acid trip, give yourself invulnerability.
- Now switch to windowed mode with alt-enter or "fullscreen 0" in the console.
Doing it in that order, all of the inverted sprites, the zombies, items, and armor all warp for me in infrared. If I give myself invulnerability instead of infrared, *everything* warps, including the ceiling, floor, sky, weapon sprite, and wall textures, like so (Just took this now with only Doom loaded, nothing else):
