Earlier quoted context omitted.
It gets called plagiarism, and there are lots of lawsuits preventing this.
It's not plagiarism at all. The AI is trained on 5 billion images yet it stores only 4gb of data. Thus it is impossible that it stores the actual work. For any image that the AI generates, you can't point to any image in the training data that the image is derived from.
I don't know if that counts as plagiarism, but there's clearly some use of this copyright material that the authors probably didn't envision and did not grant permission for. I have no idea what the law would be in cases like this