Steps to reproduce:

1. Install CentOS Stream 9.
2. Run

   # dnf update -y
   

1. Install and enable each Zabbix server, frontend, and agent2 services in the host.
2. Install zabbix-get package.
3. Run

   # zabbix_get -s 127.0.0.1 -k 'systemd.unit.get[zabbix-agent2.service]'

Result:
First time:

# zabbix_get -s 127.0.0.1 -k 'systemd.unit.get[zabbix-agent2.service]'
ZBX_NOTSUPPORTED: Cannot get unit property: dbus: wire format error: unexpected EOF

After the second time:

# zabbix_get -s 127.0.0.1 -k 'systemd.unit.get[zabbix-agent2.service]'
ZBX_NOTSUPPORTED: Cannot get unit property: dbus: connection closed by user 

systemd.unit.info has same problem.
Expected:
It returns systemd unit informations.