Cluster operator monitoring degraded with error "openshift-monitoring/prometheus-operator-admission-webhook: got 1 unavailable replicas"

Issue

• After the upgrade, it was identified that the monitoring cluster operator entered into a degraded state with an error:

$ oc describe co monitoring
===Output-Trimmed===
message: Failed to rollout the stack. Error: updating prometheus operator: reconciling Prometheus Operator Admission Webhook Deployment failed: updating Deployment object failed: waiting for DeploymentRollout of openshift-monitoring/prometheus-operator-admission-webhook  got 1 unavailable replicas
reason: UpdatingPrometheusOperatorFailed
    status: 'True'
    type: Degraded
===Output-Trimmed===