reported in https://forum.matomo.org/t/geoip2autoupdater-failed-to-unzip-the-downloaded-file-is-not-a-valid-geolocation-database/43925 (and also found in my cronjob)
Whenever a GeoIP2 update job falls at the start of a month it might be possible that the
dbip-city-lite-2021-12.mmdb.gz doesn't exist on the servers and the update fails
ERROR [2021-12-01 02:03:30] 895774 /var/www/matomo/plugins/GeoIp2/GeoIP2AutoUpdater.php(189): GeoIP2AutoUpdater: failed to unzip '/var/www/matomo/tmp/latest/DBIP-City.mmdb.gz.download' after downloading 'https://download.db-ip.com/free/dbip-city-lite-2021-12.mmdb.gz': The downloaded file is not a valid geolocation database. Please re-check the URL or download the file manually. [Query: , CLI mode: 1]
In case a 404 is returned, Matomo could fetch the previous months file again or reschedule the job for a few hours later.