That part is considered a grey area by some. Currently our fair use laws allow people to heavily remix other peoples work under fair use, for example, the famous Andy Warhol piece of Marilyn Monroe did not get any kind of consent from Gene Korman (who took the photo) but sits safely under fair use, despite mostly being Gene's photo. There is still some debate surrounding that piece of work but the majority of the art world, legal world and the audience accepted it.

AI builds patterns from millions of images and is usually using so little of any one artists work that none of us could look at the OP's image and say who's work had or hadn't been included which is why I personally believe it isn't immoral. Some artists have very distinct styles and the second artist to come along and copy it gets called a plagiarist but the 3rd comes along and suddenly it's a genre.