Ubuntu has a track record to do their own thing and splitting communitySee also Canonical's upstart init system, when most embraced systemd.
If you weren't aware, Nextcloud provides non-AIO compose files in their docker repo: https://github.com/nextcloud/docker/blob/master/.examples/docker-compose/with-nginx-proxy/postgres/fpm/docker-compose.yml
NVMe drives aren't guaranteed to be fast. Based on those stats I'm guessing you have QLC and no DRAM.
What method did you use to determine the pressure advance value and what value did you select? If the number is too large you will get very odd behavior.
See also Canonical's upstart init system, when most embraced systemd.