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))

* 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))

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

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

        * 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

  - `spec.version` is removed in v1; use `spec.versions` instead
  - `spec.validation` is removed in v1; use `spec.versions[*].schema` instead
  - `spec.subresources` is removed in v1; use `spec.versions[*].subresources` instead
  - `spec.additionalPrinterColumns` is removed in v1; use `spec.versions[*].additionalPrinterColumns` instead

- 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))

* The --long-running-request-regexp flag to kube-apiserver is deprecated and will be removed in a future release. Long-running requests are now detected based on specific verbs (watch, proxy) or subresources (proxy, portforward, log, exec, attach). ([#38119](https://github.com/kubernetes/kubernetes/pull/38119), [@liggitt](https://github.com/liggitt))