IIUC you're saying that kube-apiserver responded Event object with empty event_time to the list_namespaced_event request. As a result this python client failed to parse the response because event_time is a required field.

This sounds like another occurrence of kubernetes-client/gen#52. The fix needs to be done in upstream Kubernetes. kube-apiserver should either respond an event_time that is not null, or the field should be marked as optional instead of required.