### Other notable changes

* Extend TLS timeouts to work around slow arm64 math/big ([#66264](https://github.com/kubernetes/kubernetes/pull/66264), [@joejulian](https://github.com/joejulian))

    *   Extends the device plugin checkpoint data to record registered resources so that we can finish resource removing devices even upon kubelet restarts.
    *   Passes sourcesReady from kubelet to the device plugin to avoid removing inactive pods during the grace period of kubelet restart.

Updated Plugin Mechanism for kubectl is Graduating to Stable ([#579](https://github.com/kubernetes/enhancements/issues/579))

- Extends functionality to kubectl to support extensions adding new commands as well as overriding specific subcommands (at any depth).
- Documentation fixes

- Kube-proxy extends the schema of its healthz/ and livez/ endpoints to incorporate information about the corresponding IP family ([#129271](https://github.com/kubernetes/kubernetes/pull/129271), [@aroradaman](https://github.com/aroradaman)) [SIG Network and Windows]...

- Extend kube-apiserver /readyz with new "informer-sync" check ensuring that internal informers are synced. ([#92644](https://github.com/kubernetes/kubernetes/pull/92644), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery and Testing]

- `kubeadm`: will now allow deploying a kubelet that is 3 versions older than the version of `kubeadm` (N-3). This aligns with the recent change made by SIG Architecture that extends the support skew between the control plane and kubelets. Tolerate this new kubelet skew for the commands `init`, `join` and `upgrade`. Note that if the `kubeadm` user applies a control plane version that is older than the `kubeadm` version (N-1 maximum)...

- Extend kube-apiserver /readyz with new "informer-sync" check ensuring that internal informers are synced. ([#92644](https://github.com/kubernetes/kubernetes/pull/92644), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery and Testing]

- Extend kube-apiserver /readyz with new "informer-sync" check ensuring that internal informers are synced. ([#92644](https://github.com/kubernetes/kubernetes/pull/92644), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery and Testing]

- Only extend token lifetimes when `--service-account-extend-token-expiration` is true and the requested token audiences are empty or exactly match all values for `--api-audiences`. ([#105954](https://github.com/kubernetes/kubernetes/pull/105954), [@jyotimahapatra](https://github.com/jyotimahapatra))...

  * Plugins

      * Introduces the ability to extend kubectl by adding third-party plugins. Developer preview, please refer to the documentation for instructions about how to use it. ([#37499](https://github.com/kubernetes/kubernetes/pull/37499), [@fabianofranz](https://github.com/fabianofranz))