I only now encountered this 2022 preprint from Ehsan Kianfar: www.researchsquare.com/article/rs-1... 2/3 of it are the 302 references. 20% of those are irrelevant, gratuitous self-citations but the rest are a snapshot of what fake journals & papers the citation brokers were paying authors to cite.

Should add that Kianfar is a highly productive author, as evinced by a substantial presence in PubPeer threads. pubpeer.com/search?q=%28...