one year passed… As a workaround one may try 2 commands:
echo -e ":msg, contains, \"Invalid hostname [scrubbed]\" stop\n:msg, contains, \"No more HSDir available to query.\" stop"|sudo tee -a /etc/rsyslog.d/123-custom.conf
sudo systemctl restart rsyslog.service && systemctl status rsyslog.service
Journalctl continue to show that lines, but log files no longer contain it IMO.