Didn't hear about paper mills until today...
Prospective buyers can see the paper’s title, and sometimes its abstracts, as well as the expected ranking in the citation database Scopus of the journal of publication. They then select an author slot, with costs ranging from about US$500 to $3,000. The company promises that titles and abstracts shown online will be “completely changed” for publication. “No one will ever be able to find the manuscript anywhere,” the website declares.
AI is making this kind of scam much easier to perpetrate...