By default K8S overwrites source client(host) IP with IP from kubernetes internal network.

Because of that when host is registered in Zabbix, it has k8s network IP instead of registred host IP.

To change that, externalTrafficPolicy option should be set to Local in K8S service, but official Zabbix helm chart does not supporting such option currently.

More informations:
https://kubernetes.io/docs/tasks/access-application-cluster/create-external-load-balancer/#annotation-to-modify-the-loadbalancer-behavior-for-preservation-of-source-ip