Here is the output when executing with -vv
OMD[mysite]:~$ /omd/sites/mysite/share/check_mk/agents/special/agent_proxmox_ve -vv '-u' 'checkmk@pve' '-p' 'PASSWORD' '--port' 8006 '--no-cert-check' '--timeout' 60 'pveiloon'
INFO 2022-09-05 11:46:39 root: running file /omd/sites/mysite/lib/python3/cmk/special_agents/utils/agent_common.py
INFO 2022-09-05 11:46:39 root: using Python interpreter v3.9.10.final.0 at /omd/sites/mysite/bin/python3
DEBUG 2022-09-05 11:46:39 root: args: {'debug': False, 'verbose': 2, 'vcrtrace': False, 'timeout': 60, 'port': 8006, 'username': 'checkmk@pve', 'password': 'PASSWORD', 'log_cutoff_weeks': 2, 'dump_logs': False, 'no_cert_check': True, 'hostname': 'pveiloon'}
INFO 2022-09-05 11:46:39 agent_proxmox_ve: Establish connection to Proxmox VE host 'pveiloon'
INFO 2022-09-05 11:46:39 agent_proxmox_ve: Fetch general cluster and node information..
INFO 2022-09-05 11:46:40 agent_proxmox_ve: Fetch and process backup logs..
DEBUG 2022-09-05 11:46:40 cmk.special_agents.utils.misc: Cache: loaded 6 elements
INFO 2022-09-05 11:46:40 agent_proxmox_ve: BackupTask('vzdump', t='2022.09.04-20:30:01', vms=('101',))
DEBUG 2022-09-05 11:46:40 agent_proxmox_ve: {'101': {'started_time': '2022-09-04 20:30:01', 'transfer_size': 1429365116109, 'transfer_time': 1501, 'total_duration': 1505.0}}
Caught unhandled TypeError('NoneType' object is not iterable) in /omd/sites/mysite/lib/python3/cmk/special_agents/utils/agent_common.py:135
Thanks for trying to help 
Best regards,
pixelpoint