* Updating federation.v1beta1.Cluster API to disallow subdomains as valid cluster names. Only DNS labels are allowed as valid cluster names now.
* [Kubelet] Rename `--config` to `--pod-manifest-path`. `--config` is deprecated. ([#29999](https://github.com/kubernetes/kubernetes/pull/29999), [@mtaufen](https://github.com/mtaufen))

- Added a alpha feature, behind the `RelaxedEnvironmentVariableValidation` feature gate.
  When that gate is enabled, Kubernetes allows almost all printable ASCII characters to be used in the names
  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))

  * For all other existing controllers except StatefulSet, this has no effect on
    the ability of the controller to replace pods because the controllers do not
    reuse pod names (they use generate-name).
  * User-written controllers that reuse names of pod objects should evaluate this change.
  * When deleting an object with `kubectl delete ... --grace-period=0`, the client will