This release SIG API Machinery focused mainly on CustomResources. For example, subresources for CustomResources are now beta and enabled by default. With this, updates to the `/status` subresource will disallow updates to all fields other than `.status` (not just `.spec` and `.metadata` as before). Also, `required` and `description` can be used at the root of the CRD OpenAPI validation schema when the `/status` subresource is enabled.

* Advanced audit policy now supports matching subresources and resource names, but the top level resource no longer matches the subresouce. For example "pods" no longer matches requests to the logs subresource of pods. Use "pods/logs" to match subresources. ([#48836](https://github.com/kubernetes/kubernetes/pull/48836), [@ericchiang](https://github.com/ericchiang))

### Instrumentation

* For advanced auditing, audit policy supports subresources wildcard matching, such as "resource/", "/subresource","*". ([#55306](https://github.com/kubernetes/kubernetes/pull/55306), [@hzxuzhonghu](https://github.com/hzxuzhonghu))

- Kube-apiserver: Made the subresources `pods/exec`, `pods/attach`, and `pods/portforward` require `create` permission for both SPDY and Websocket API requests. Previously, SPDY requests required `create` permission, but Websocket requests only required `get` permission. This change...

* Audit policy supports matching subresources and resource names, but the top level resource no longer matches the subresouce. For example "pods" no longer matches requests to the logs subresource of pods. Use "pods/logs" to match subresources. ([#48836](https://github.com/kubernetes/kubernetes/pull/48836), [@ericchiang](https://github.com/ericchiang))

- In clusters where the DryRun feature is enabled, dry-run requests...

    * The body size limit does not apply to subresources like pods/proxy that proxy request content to another server.

- Removed restrictions on subresource flag in kubectl commands ([#128296](https://github.com/kubernetes/kubernetes/pull/128296), [@AnishShah](https://github.com/AnishShah)) [SIG CLI]
- Revised the kubelet API Authorization with new subresources, that allow finer-grained authorization checks and access control for kubelet endpoints.

        * requests from a node for a TLS client certificate for itself are approved if the CSR creator has `create` permission on the `certificatesigningrequests` resource and the `selfnodeclient` subresource in the `certificates.k8s.io` API group

- An alpha flag `--subresource` is added to get, patch, edit replace kubectl commands to fetch and update status and scale subresources. ([#99556](https://github.com/kubernetes/kubernetes/pull/99556), [@nikhita](https://github.com/nikhita))