This is a mixed issue, where Pi-hole's recently updated blocklist import may show misleading information or some false positives, but it indeed also helped to reveal a few incorrect entries in Steven Black's adlists.
As far as I can tell, both sides are working on their respective fixes. 
Ours can be tracked via GitHUb, see Impartially report the number of domains imported from any given adlist by PromoFaux 路 Pull Request #5130 路 pi-hole/pi-hole 路 GitHub and Reduce number of false positives when gravity unable to import domains - change the wording of the output by PromoFaux 路 Pull Request #5128 路 pi-hole/pi-hole 路 GitHub .