The disadvantage of AI generated images is that they are not copyright protected. You can make your game with the images, even sell them on Patreon, but you have no rights if someone comes and copies your images. This someone then of course also has no rights if something is stolen from his game again.
This is the only difference why normal artwork is better than AI artwork. You have more legal possibilities to act against the theft of the images. But if an image has no copyright as it is the case with AIs, then you can not take legal action against it.
For this game you can say that Dark Cookie probably has all the rights to take action against these artworks. Because Dark Cookie still draws completely by himself, ergo the copyright on his pictures lies with him and actually not everyone is allowed to use them.
This is the only difference why normal artwork is better than AI artwork. You have more legal possibilities to act against the theft of the images. But if an image has no copyright as it is the case with AIs, then you can not take legal action against it.
For this game you can say that Dark Cookie probably has all the rights to take action against these artworks. Because Dark Cookie still draws completely by himself, ergo the copyright on his pictures lies with him and actually not everyone is allowed to use them.