It looks like scammers are scraping genuine art sites, like deviant art, and creating NFTs from the rework for which they have no rights to.
After 18 years showcasing his art on Deviant Art, he is taking his art offline.
It looks like the NFT sites aren’t doing any due diligence, and it sounds like they just shrug their shoulders, when they are informed of the cases of fraud. As long as they make their commissions, they don’t seem to worry about the legality of the NFTs.