I think the early access model has worked so far, (meaning Rowling and her lawyers have allowed it to happen). I suspect if the money being made exceeds a certain amount they'll probably sue Patreon or something. Unless patreon's terrible business decisions cause it to collapse first lol.
5 years ago all authors dared to do was to publish another book and advertise it using their fanfiction. Occasionally they'd ask for Kofi too.
Rowling already stopped a certain wiki site (which she admitted to using herself lol!) from publishing a kind of encyclopaedic book on the world of Harry Potter iirc. Though it could be argued that they were just reusing content which is the closest thing to plagiarism but not plagiarism.