If you have installed istio-operator in a project/namespace other than "openshift-operators" before, we need delete the following Validation Webhook Configuration before reinstalling istio-operator using OLM. ( oc delete -f servicemesh-operator.yaml won't delete that Validation Webhook Configration )

[operator namespace].servicemesh-resources.maistra.io is listed under the following OCP console URL:

https://[your ocp api server url].devcluster.openshift.com/k8s/cluster/admissionregistration.k8s.io~v1beta1~ValidatingWebhookConfiguration/

Otherwise, you will get error when apply a CR.

Internal error occurred: failed calling webhook "smcp.validation.maistra.io": Post https://admission-controller.istio-operator.svc:443/validate-smcp?timeout=30s: service "admission-controller" not found