After a restart, the service still does not start. I get no notification about the systemd-quotacheck.service failing, so it must be ok. I honestly don't understand what this plesk-ext-monitoring-hcd.service is supposed to do. As far as I can see, monitoring (grafana) does work.
Operating System - Debian 10.13
Plesk Obsidian Version 18.0.58 Update #2
I have the same problem with plesk-ext-monitoring-hcd.service:
Execution status has failed with exit code 3, stdout: ● plesk-ext-monitoring-hcd.service - Hardware changes detector for the Plesk Monitoring
Loaded...