Newer writers, just don't fucking use "AI" for anything, ever2. But also, the concern here is slightly different: The issue appears not to be that “AI” material isn’t copyrightable, the issue is that “AI” is trained on copyrighted material, so prose generated from it could be contested by the original copyright holders. Don’t incorporate it into your writing process; every part of the process needs to be demonstrably free of any “AI” input because “AI” training data is full of other people’s copyrights. Don’t incorporate “AI” into any part of your publishing process, either: Don’t use “AI” editing, don’t use “AI” art, don’t use “AI” translation, don’t use “AI” anything that calls into dispute whether your work is actually yours. Using “AI” cover art, for example, will immediately call into question what else in the book is “AI.”