But anyway you don't need NAT reflection on pfSense for this now. It's useless, since nothing points to its WAN IP.
And the port forwarding rule with the WAN IP is useless as well.
@viragomann no I need both, I tested it. As soon as I remove the reflection from the port forward, the service is not accessible from within LAN. If I deactivate the WAN port forward Rule, I can't access it from the internet. Maybe because of the first main forward "everything" to pfsense rule in proxmox's network interfaces file. So I will leave as it is for now. I'm just happy that it finally works.
Yes, got a scheduled job doing VM backups every day.