Hi, PowerDNS dev here! Would you mind fixing your handling of NODATA answers, which are currently lacking the AA bit and a SOA record in authority? It does not seem to affect all instances, so perhaps it only happens on the legacy infra.
You can get the details here, for example: https://dnsviz.net/d/b.b.b.b.b.b.b.b.a.a.a.a.a.a.nope.repl.c...