After uninstalling the old version and installing the new version, the add-on starts.
However, I still have the problem that I receive a message from the unbound log, but a blocked address is still loaded.
I had posted the reason for this elsewhere in this forum but didn’t find a real solution, or rather, no one addressed it. It also had a different context, but here I see the problem.
My Squid proxy uses an upstream http proxy that is also used as a DNS server and the DNS query reaches this server despite the blocklist. Unfortunately, I don’t know why this is the case.
If I disable the upstream proxy, everything is blocked correctly.