At least in Murican law I'm pretty sure any use of any image that's not public domain could technically be flagged.
Ignoring the legal, morally and just generically, t's good know the origin if you use it routinely. If nothing else someone might ask if they think it looks good. I'm kind of a pic/meme hoarder that wouldn't be able to tell you where the specific origin of most are though.
Multi comms is likely an instance ban, which they hand out freely on the .ml instance for anyone not in line with their ideology.