- CSI Migration: Fixes issue where all volumes with the same inline volume inner spec name were staged in the same path. Migrated inline volumes are now staged at a unique path per unique volume. ([#84754](https://github.com/kubernetes/kubernetes/pull/84754), [@davidz627](https://github.com/davidz627))

* Fix metrics API group name in audit configuration ([#53493](https://github.com/kubernetes/kubernetes/pull/53493), [@piosz](https://github.com/piosz))
* GCE: Fixes ILB sync on legacy networks and auto networks with unique subnet names ([#53410](https://github.com/kubernetes/kubernetes/pull/53410), [@nicksardo](https://github.com/nicksardo))

- The calculation of pod UIDs for static pods has changed to ensure each static pod gets a unique value - this will cause all static pod containers to be recreated/restarted if an in-place kubelet upgrade from 1.20 to 1.21 is performed. Note that draining pods before upgrading the kubelet across minor versions is the supported upgrade path. (...

* GCE: Fixes ILB sync on legacy networks and auto networks with unique subnet names ([#53410](https://github.com/kubernetes/kubernetes/pull/53410), [@nicksardo](https://github.com/nicksardo))

- In the course of admitting a single request, the ValidatingAdmissionPolicy plugin will perform no more than one authorization check per unique authorizer expression. All evaluations of identical authorizer expressions will produce the same decision. ([#116443](https://github.com/kubernetes/kubernetes/pull/116443), [@benluddy](https://github.com/benluddy)) [SIG API Machinery and Testing]...

* kubelet: resolved hang/timeout issues when running large numbers of pods with unique configmap/secret references ([#74755](https://github.com/kubernetes/kubernetes/pull/74755), [@liggitt](https://github.com/liggitt))

* kubelet: resolved hang/timeout issues when running large numbers of pods with unique configmap/secret references ([#74755](https://github.com/kubernetes/kubernetes/pull/74755), [@liggitt](https://github.com/liggitt))

- CustomResourceDefinition schemas that use `x-kubernetes-list-type: map` or `x-kubernetes-list-type: set` now enable validation that the list items in the corresponding custom resources are unique. ([#84920](https://github.com/kubernetes/kubernetes/pull/84920), [@sttts](https://github.com/sttts)) [SIG API Machinery]
 
#### Configuration file changes:

#### kube-apiserver:

strategicmerge patchMergeKey for VolumeMounts was changed from "name" to "mountPath".  This was necessary because the name field refers to the name of the Volume, and is not a unique key for the VolumeMount.  Multiple VolumeMounts will have the same Volume name if mounting the same volume more than once.  The "mountPath" is verified to be unique and can act as the mergekey.  ([#35071](https://github.com/kubernetes/kubernetes/pull/35071), [@pwittrock](https://github.com/pwittrock))

## Deprecations...

  - `admissionReviewVersions` default value is removed and the field made required for v1 (supported versions for AdmissionReview are `v1` and `v1beta1`)
  - The `name` field for specified webhooks must be unique for `MutatingWebhookConfiguration` and `ValidatingWebhookConfiguration` objects created via `admissionregistration.k8s.io/v1`