failed trust-anchor-telemetry queries

[Klaus Darilion]

Hello!

Bind version: 9.16.19-1+ubuntu18.04.1+isc+1

Recently I discovered these logs:
09:13:12 named[3234]: _default: sending trust-anchor-telemetry query '_ta-0000/NULL'
09:13:12 named[3234]:   validating ./NSEC: no valid signature found
09:13:12 named[3234]:   validating ./SOA: no valid signature found
09:13:12 named[3234]:   validating ./NSEC: no valid signature found
09:13:12 named[3234]:   validating ./SOA: no valid signature found
09:13:12 named[3234]: no valid RRSIG resolving '_ta-0000/DS/IN': 2001:503:ba3e::2:30#53
09:13:13 named[3234]:   validating ./SOA: no valid signature found
09:13:13 named[3234]:   validating ./NSEC: no valid signature found
09:13:13 named[3234]: no valid RRSIG resolving '_ta-0000/DS/IN': 2001:dc3::35#53
09:13:13 named[3234]:   validating ./SOA: no valid signature found
09:13:13 named[3234]:   validating ./NSEC: no valid signature found
09:13:13 named[3234]: no valid RRSIG resolving '_ta-0000/DS/IN': 2001:7fe::53#53
09:13:13 named[3234]:   validating ./NSEC: no valid signature found
09:13:13 named[3234]:   validating ./SOA: no valid signature found
09:13:13 named[3234]: no valid RRSIG resolving '_ta-0000/DS/IN': 2001:500:1::53#53
09:13:13 named[3234]:   validating ./SOA: no valid signature found
09:13:13 named[3234]:   validating ./NSEC: no valid signature found
09:13:13 named[3234]: no valid RRSIG resolving '_ta-0000/DS/IN': 2001:500:9f::42#53
09:13:13 named[3234]:   validating ./SOA: no valid signature found
...

The config of the name server is authoritative-only, hence:
        allow-recursion {
                none;
        };

May it be, that due to disabled recursion, these trust-anchor queries are failing? Or what might be other reasons?

Thanks
Klaus