I'm pretty sure Cloudflare is an ISP according to German law ("Diensteanbieter" according to DDG). You might confuse "ISP" with the terminology of "Access Provider" according to the (now defunct) §8 TMG.
If that were true, sci-hub.se would be blocked in Germany on 1.1.1.1 (1dot1dot1dot1.cloudflare-dns.com), it isn't blocked, therefore it's not true. (Modus tollens)
If that were true, sci-hub.se would be blocked in Germany on 1.1.1.1 (1dot1dot1dot1.cloudflare-dns.com), it isn't blocked, therefore it's not true. (Modus tollens)