- Adds feature gate `KubeletInUserNamespace` which enables support for running kubelet in a user namespace.
  
  The user namespace has to be created before running kubelet.
  All the node components such as CRI need to be running in the same user namespace.
  

* The `--authorization-rbac-super-user` flag (alpha in 1.5) is deprecated; the `system:masters` group has privileged access ([#38121](https://github.com/kubernetes/kubernetes/pull/38121), [@deads2k](https://github.com/deads2k))

    * 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

- Kubeadm: `kubeadm upgrade node` now supports `addon` and `post-upgrade` phases. User can use `kubeadm upgrade node phase addon` to execute the addon upgrade, or use `kubeadm upgrade node --skip-phases addon` to skip the addon upgrade. Currently, the `post-upgrade` phase is no-op, and it is mainly used to handle some release specific post-upgrade tasks. ([#127242](https://github.com/kubernetes/kubernetes/pull/127242), [@SataQiu](https://github.com/SataQiu))...

  - `alpha` support (guarded by the `ServiceAccountTokenPodNodeInfo` feature gate) for including the node name (and uid, if the node exists) as additional claims in service account tokens it issues which are bound to pods, and `authentication.kubernetes.io/node-name` and `authentication.kubernetes.io/node-uid` extra user info when the token is used to authenticate.

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

- kubeadm: make the command "kubeadm alpha kubeconfig user" accept a "--config" flag and remove the following flags:
  - apiserver-advertise-address / apiserver-bind-port: use either localAPIEndpoint from InitConfiguration or controlPlaneEndpoint from ClusterConfiguration.
  - cluster-name: use clusterName from ClusterConfiguration

- Removed a warning around Linux user namespaces and kernel version. If the feature gate `UserNamespacesSupport` was enabled, the kubelet previously warned when detecting a Linux kernel version earlier than 6.3.0. User namespace support on Linux typically does still need kernel 6.3 or...

- 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]

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....