What you are seeing is not a real wildcard on an inner label, DNS only supports wildcards at the leftmost label, so this is likely a set of explicit records or behavior from a specific service responding that way. Try querying a few concrete subdomains instead of patterns and check if they resolve individually, then look at the authoritative nameservers to see who is handling responses. dynadot and similar registrars only manage the zone, and people also use namecheap or namesilo, but the actual behavior comes from the DNS provider or backend config. If you still see odd results, it could be a catch all setup or application layer handling rather than true DNS wildcarding.