- Kubeadm: graduate the command `kubeadm alpha kubeconfig user` to `kubeadm kubeconfig user`. The `kubeadm alpha kubeconfig user` command is deprecated now. ([#97583](https://github.com/kubernetes/kubernetes/pull/97583), [@knight42](https://github.com/knight42)) [SIG Cluster Lifecycle]

    *  - User should be able to create k8s cluster which spans across multiple ESXi clusters, datacenters or even vCenters.
    *  - vSphere cloud provider (VCP) uses OS hostname and not vSphere Inventory VM Name.
    *    That means, now  VCP can handle cases where user changes VM inventory name.

* Controller-manager --service-sync-period flag has been removed. (It was never used in the code and should have no user impact.) ([#59359](https://github.com/kubernetes/kubernetes/pull/59359), [@khenidak](https://github.com/khenidak))

* [beta] SelfSubjectRulesReview, an API that lets a user see what actions they can perform with a namespace, has been added to the authorization.k8s.io API group. This bulk query is intended to enable UIs to show/hide actions based on the end user, and for users to quickly reason about their own permissions.

kustomize, so there are a few backwards-incompatible changes, most of which are rare use cases, bug fixes with side effects, or things that have been deprecated for multiple releases already:
  
  - https://github.com/kubernetes-sigs/kustomize/pull/4911: Drop support for a very old, legacy style of patches. patches used to be allowed to be used as an alias for patchesStrategicMerge in kustomize v3. You now have to use patchesStrategicMerge explicitly, or update to the new syntax supported by patches....

    * for the kubelet is used, and is expected to be present in `/var/lib/kubelet/config.yaml`.
    * For runtime-detected, instance-specific configuration values, a environment file with
    * dynamically-generated flags at `kubeadm init` or `kubeadm join` run time is used.
    * Finally, if the user wants to override something specific for the kubelet that can't be done via

- Kubelet: a configuration file specified via `--config` is now loaded with strict deserialization,...

- The RuntimeClass API has been added. This feature is in alpha, and the RuntimeClass feature gate must be enabled in order to use it. The RuntimeClass API resource defines different classes of runtimes that may be used to run containers in the cluster. Pods can select a RuntimeClass to use via the RuntimeClassName field. ([#67737](https://github.com/kubernetes/kubernetes/pull/67737), [@tallclair](https://github.com/tallclair))

  - All resources under `apps/v1beta1` and `apps/v1beta2` - use `apps/v1` instead
  - `daemonsets`, `deployments`, `replicasets` resources under `extensions/v1beta1` - use `apps/v1` instead
  - `networkpolicies` resources under `extensions/v1beta1` - use `networking.k8s.io/v1` instead

- Klog text output now uses JSON as encoding for structs, maps and slices. ([#117687](https://github.com/kubernetes/kubernetes/pull/117687), [@pohly](http...