This hostname points at the in-cluster K8sGPT operator (controller). There is no browser UI on the operator itself.
Use the K8sGPT CLI (k8sgpt analyze) and Kubernetes resources such as K8sGPT / Result CRDs in your cluster.
The operator’s metrics endpoint is protected by kube-rbac-proxy (Kubernetes bearer token required). A plain browser request there returns Unauthorized; that is expected.