From `#gnupg` channel on 2025-03-18, I read about this.
To replicate, here is the scenario:
```
$ export GNUPGHOME=/tmp/gnupg-testing
$ mkdir -m 0700 $GNUPGHOME
$ echo use-keyboxd >$GNUPGHOME/common.conf
$ gpg -recv-keys 0xD9F31F5F75F9B14D
$ gpg -k '<jrm@FreeBSD.org>' # Note that we use <..> style address here and it includes uppercase letters.
gpg: error reading key: No public key
# key should be available, but failure
$ gpg-connect-agent --hex --keyboxd "SEARCH --openpgp -- <jrm@FreeBSD.org>" /bye
ERR 134217755 Not found <Keybox>
```