This is a deliberately broken DNSSEC test zone: its DS and DNSKEY records announce ECDSAP256SHA256 (algorithm 13), but all RRSIGs are stripped from the zone — no signatures are served at all.
Every validating resolver should treat this zone as bogus. If you can see this page, your resolver does not validate DNSSEC. This zone is the control for the ML-DSA-44 test zones under alg18.westerbaan.name (per draft-westerbaan-dnssec-mldsa): it shows what a validation failure looks like without any post-quantum algorithms involved.
Try: dig +dnssec broken13.alg18.westerbaan.name A