- Add a configuration field to shorten the timeout of validating/mutating admission webhook call. The timeout value must be between 1 and 30 seconds. Default to 30 seconds when unspecified.  ([#74562](https://github.com/kubernetes/kubernetes/pull/74562), [@roycaihw](https://github.com/roycaihw))

* Fix kubelet PVC stale metrics ([#59170](https://github.com/kubernetes/kubernetes/pull/59170), [@cofyc](https://github.com/cofyc))
* Fix panic create/update CRD when mutating/validating webhook configured. ([#61404](https://github.com/kubernetes/kubernetes/pull/61404), [@hzxuzhonghu](https://github.com/hzxuzhonghu))

- kube-apiserver: setting a `dryRun` query parameter on a CONNECT request will now cause the request to be rejected, consistent with behavior of other mutating API requests. Examples of CONNECT APIs are the `nodes/proxy`, `services/proxy`, `pods/proxy`, `pods/exec`, and `pods/attach` subresources. Note that this prevents sending a `dryRun` parameter to backends via `{nodes,services,pods}/proxy` subresources....

* API server now has two separate limits for read-only and mutating inflight requests. ([#36064](https://github.com/kubernetes/kubernetes/pull/36064), [@gmarek](https://github.com/gmarek))

  // string is empty, no mutation has occurred. Otherwise the string is a
  // description of the mutation suitable for returning to the user.
  //
  // Sessions are added to this map in TF_NewSession, and removed in
  // TF_DeleteSession.
  // TF_Graph may only / must be deleted when
  //   sessions.size() == 0 && delete_requested == true
  //
  // TODO(b/74949947): mutations currently trigger a warning instead of a bad

- Changed apiserver to treat failures decoding a mutating webhook patch as failures to call the webhook so they trigger the webhook failurePolicy and count against metrics like `webhook_fail_open_count` ([#131627](https://github.com/kubernetes/kubernetes/pull/131627), [@dims](https://github.com/dims)) [SIG...

* kubeadm - Increase the manifest upgrade timeout to make upgrades more reliable. ([#65029](https://github.com/kubernetes/kubernetes/pull/65029), [@detiber](https://github.com/detiber))
* Webhooks for the mutating admission controller now support "remove" operation. ([#64971](https://github.com/kubernetes/kubernetes/pull/64971), [@sttts](https://github.com/sttts))

 * this structure is never mutated, it provides a thread-safe view of the backing map.
 *
 * <p>The {@link MapIteratorCache} assumes ownership of the backing map, and cannot guarantee
 * correctness in the face of external mutations to the backing map. As such, it is <b>strongly</b>
 * recommended that the caller does not persist a reference to the backing map (unless the backing
 * map is immutable).
 *

- The kube-apiserver now resets `managedFields` that got corrupted by a mutating admission controller. ([#98074](https://github.com/kubernetes/kubernetes/pull/98074), [@kwiesmueller](https://github.com/kwiesmueller))

  - **apiserver_flowcontrol_watch_count_samples**: histograms of number of watches relevant to a given mutating request, broken down by that request's priority_level and flow_schema. ([#105873](https://github.com/kubernetes/kubernetes/pull/105873), [@MikeSpreitzer](https://github.com/MikeSpreitzer)) [SIG API Machinery, Instrumentation and Testing]