The domain home64.de is not listed on the Public Suffix List, so if that is not your domain, but it is a shared domain that allocates individual subdomains to different users, that is going to account for the problem.
The rate limits will apply across home64.de which means the ability of subdomain holders to obtain Let's Encrypt certificates will be severely impacted. You may want to get your domain that you dont share with other unrelated parties.