Somehow ironic: I'm now using the DNS-over-TLS [directly in the FritzBox] from CleanBrowsing, which provides "porn filtering" for "concerned parents" (why do I think that they're "concerned" about evil people like me, too?). However they have also a DNS that blocks only malware, and they promise to not log any requests. So I'll give it a try in combination with Quad9. 😀

(Even if both would log, I think it would still be better than leaving the complete DNS history at my ISP.)