I just finished skimming through “How reliable and useful is Cabell’s Blacklist ? A data-driven analysis” by Christophe Dony , Maurane Raskinet, François Renaville, Stéphanie Simon, and Paul Thirion, appearing in LIBER Quarterly.
It appears to be well-done and worth reading. I’m biased, to be sure, since the study relies on my own work on questionable journals and the blacklist.