### API Change

### API Change

 - For all kinds in the API group version, a spec.selector default value is no longer
 available, because it's incompatible with `kubectl
 apply` and strategic merge patch. You must explicitly set the spec.selector value
 in your manifest. An object with a spec.selector value that does not match the labels in
 its spec.template is invalid.

 - Selector mutation is disabled for all kinds in the

  - kube-proxy addon starts to use the label `node.kubernetes.io/kube-proxy-ds-ready` instead of `beta.kubernetes.io/kube-proxy-ds-ready` as its node selector.
  - metadata-proxy addon starts to use the label `cloud.google.com/metadata-proxy-ready` instead of `beta.kubernetes.io/metadata-proxy-ready` as its node selector.

#### Storage

* Improving the performance of Endpoint and EndpointSlice controllers by caching Service Selectors ([#84280](https://github.com/kubernetes/kubernetes/pull/84280), [@gongguan](https://github.com/gongguan))

### API Change

is evaluated the oldObject and newObject that would be sent to the webhook, and is considered to match if either object matches the selector. A null object (oldObject in the case of create, or newObject in the case of delete) or an object that cannot have labels (like a DeploymentRollback or a PodProxyOptions object) is not considered to match. Use the object selector only if the webhook is opt-in, because end users may skip the admission webhook by setting the labels. ([#78505](https://github.co...

  - `create service externalname` ([#34789](https://github.com/kubernetes/kubernetes/pull/34789), [@adohe](https://github.com/adohe))
- `set selector` - update selector labels ([#38966](https://github.com/kubernetes/kubernetes/pull/38966), [@kargakis](https://github.com/kargakis))

- Services implemented a field selector for the ClusterIP and Type fields.

* Deployment will stop adding pod-template-hash labels/selector to ReplicaSets and Pods it adopts. Resources created by Deployments are not affected (will still have pod-template-hash labels/selector).  ([#61615](https://github.com/kubernetes/kubernetes/pull/61615), [@janetkuo](https://github.com/janetkuo))