gpg since version 2.2.28 fails to get a key from a keyserver by email address using --locate-key with the error message: "Invalid user ID".
❯ gpg --homedir="$(mktemp -d)" --auto-key-locate clear,nodefault,keyserver --locate-external-key email@example.com gpg: keybox '/tmp/tmp.rBu85OTSb3/pubring.kbx' created gpg: /tmp/tmp.rBu85OTSb3/trustdb.gpg: trustdb created gpg: error retrieving 'firstname.lastname@example.org' via keyserver: Invalid user ID gpg: error reading key: Invalid user ID
Arguments without an "@" result in the (to be expected) error: "No public key".
Using --locate-key with a fingerprint or key-ID still works as expected.
This appears to not be related to a specific keyserver.
It worked in version 2.2.27.