The Legality of Rare Deep Learning

I was generating artwork. And the tags that I used were children's book, art cover, monkey hanging from tree. But then in one of them, I saw a watermark, it generated a watermark. So this data was obviously generated from images that they did not have the rights or I guess legal right to use within their training models. Where does something like that begin and end from a legality issue? We're going to see many more cases with artists and copyright infringement.