The HQSL was signed, but OpenPGP.js could not parse the signature, it did not validate, or it otherwise does not conform to HQSL standard.
There's a valid signature by an available signer key, but that signer key has no certification by any of the trusted keys for the time range given in the QSO.
Could not acquire the signer public key from key servers. This may be because they were unreachable or timed out.
The HQSL is not signed at all, though it may be valid otherwise.
The HQSL is completely valid, everything checks out.
Verification verdict