* 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

* 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))

* e2e tests that require SSH may be used against clusters that have nodes without external IP addresses by setting the environment variable `KUBE_SSH_BASTION` to the `host:port` of a machine that is allowed to SSH to those nodes.  The same private key that the test would use is used for the bastion host.  The test connects to the bastion and then tunnels another SSH connection to the node. ([#72286](https:/...

- Kubeadm: added the ControlPlaneKubeletLocalMode feature gate. It can be used to tell kubeadm to use the local kube-apiserver endpoint for the kubelet when creating a cluster with "kubeadm init" or when joining control plane nodes with "kubeadm join".  The "kubeadm join" workflow now includes two new experimental phases called "control-plane-join-etcd" and "kubelet-wait-bootstrap" which will be used when the feature gate is enabled. This phases will be marked as non-experimental when...

[alpha] Added an `--endpoint-reconciler-type` command-line argument to select the endpoint reconciler to use. The default is to use the 'master-count' reconciler which is the default for 1.9 and in use prior to 1.9. The 'lease' reconciler stores endpoints within the storage api for better cleanup of deleted (or removed) API servers. The 'none' reconciler is a no-op reconciler, which can be used in self-hosted environments.   ([#51698](https://github.com/kubernetes/kubernetes/pull/51698), [@rphill...

* [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.

* `kubectl create rolebinding` and `kubectl create clusterrolebinding` invocations must be updated to  specify multiple subjects as repeated  `--user`, `--group`, or `--serviceaccount` arguments instead of comma-separated arguments to a single `--user`, `--group`, or `--serviceaccount`.  E.g. `--user=x,y` must become `--user x --user y`  ([#43903](https://github.com/kubernetes/kubernetes/pull/43903), [@xilabao](https://github.com/xilabao))


### kubeadm

- kubeadm init correctly uses `--node-name` and `--cri-socket` when `--config` option is also used ([#71323](https://github.com/kubernetes/kubernetes/pull/71323), [@bart0sh](https://github.com/bart0sh))
- kubeadm: Always pass spec.nodeName as `--hostname-override` for kube-proxy ([#71283](https://github.com/kubernetes/kubernetes/pull/71283), [@Klaven](https://github.com/Klaven))

* kubectl commands run inside a pod using a kubeconfig file now use the namespace specified in the kubeconfig file, instead of using the pod namespace. If no kubeconfig file is used, or the kubeconfig does not specify a namespace, the pod namespace is still used as a fallback. ([#44570](https://github.com/kubernetes/kubernetes/pull/44570), [@liggitt](https://github.com/liggitt))

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....