Hey, Gigaflare! A GPUCache folder shouldn’t be within the World of WarCraft folder. It’s possible this is related to Adobe if any Adobe products may have been opened recently.
Though, I’m not sure how it ended up in the World of WarCraft folder. I did find one external report of the same thing happening recently, which may be related to Telemetry and Adobe which may explain how. Since the Blizzard Application utilizes telemetry.
Just to test, the same way we reset UIs, renaming the GPUCache to GPUCache.Old and just launching World of WarCraft may be worth a try after closing Adobe and see if it reappears. Otherwise, just for security, running through security scans is advised.