Some systemd services are enabled by default and only start if a condition is met. For example the microcode service on RHEL 7 is only started if the system is no virtual machine.

systemctl status microcode.service
● microcode.service - Load CPU microcode update
Loaded: loaded (/usr/lib/systemd/system/microcode.service; enabled; vendor preset: enabled)
Active: inactive (dead)
Condition: start condition failed at Tue 2021-05-11 09:35:44 CEST; 3 weeks 6 days ago

systemctl show microcode.service | grep ConditionResult
ConditionResult=no

Please add ConditionResult to the discovery of the systemd services in zabbix agent 2, so that it's possible to filter these services.