On the black/whitelist page one can add an domain and select the type “wildcard black/whitelist”. I think this term is misleading and can be misinterpreted resulting in faulty regex. The term “wildcard” suggests one can enter common wildcard symbols like
* or ?
Although it is acknowledged that there should be some kind of regex syntax checker the issue arose from misinterpreting the term “wildcard” - and should be omitted.
As it meant to block subdomains I suggest “subdomain black/whitelist”)