AI generated fanfic is pretty new, and we don’t have an established policy per se, although we may want to think about this and establish one.
In general, we do have a policy of asking that all content be the work of the uploading author. Obviously, when writing fan fiction, the universe/fandom and the characters are not owned by the uploading author, hence the disclaimer requirement. But we don’t allow large swaths of content taken directly from the fandom, or the read-the-book stories that were all the rage for a while. So where does AI generated writing fall? I’m not entirely sure. It’s obviously not written by the uploading author, but presumably, the AI program generated content based on parameters established by the uploading author.
I’m just not sure it’s really writing in the truest sense of the word. I can’t imagine any AI program could capture a writer’s voice: the way they use language, the cadence of their writing, the unique touches that make their work stand out from other writers. I might use it to generate a rough plot outline, but I think I’m still old-fashioned enough to want the words on the page or screen to be the words I chose myself, if that makes any sense at all.