I got a message from my domain service:
During the periodic DNS Black List, we detected that a server hosting your domain was included in one of them. On date: December 23, 2019 16:09
Thanks for letting us know! I don’t see any malicious content at the reported URL, so we have asked our network provider Digital Ocean (who must submit removal requests) to contact spamhaus asking for removal.
Since it is a major holiday in many countries, I don’t think that they will get to it today, but hopefully soon.