TLD used for cluster domain contains a hyphen or number in RHOCP 4

Issue

The TLD part of the cluster domain contains a "Hyphen(-)" or "Number(1-9)" on it, and cannot pass the checks of a proper domain format.

The Authentication Cluster Operator displays this message :

 CustomRouteControllerDegraded: Ingress.config.openshift.io "cluster" is invalid: [status.componentRoutes.currentHostnames: Invalid value: "oauth-openshift.apps.example.something-demo": status.componentRoutes.currentHostnames in body must be of type hostname: "oauth-openshift.apps.example.something-demo", status.componentRoutes.defaultHostname: Invalid value: "oauth-openshift.apps.example.something-demo": status.componentRoutes.defaultHostname in body must be of type hostname: "oauth-openshift.apps.example.something-demo]"