Guessing this has to do with how China tends to turn a blind eye (although increasingly less so) to copyright and more importantly trademark infringement issues of Western intellectual properties...perhaps Unity have tried to get some Chinese developers to remove things like Marvel characters, or Mickey Mouse and it's been ignored.

I think this is actually quite interesting when Unity itself has recently posted a tutorial on using its AI tools for the AI generation of a Nintendo character called Ness (main character in an old Snes game called Earthbound if you're not familiar)...seems a bit of a double standard if the complaint IS in fact in relation to trademark infringements.