- Kubeadm: on kubeconfig certificate renewal, keep the embedded CA in sync with the one on disk ([#88052](https://github.com/kubernetes/kubernetes/pull/88052), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]
- Kubeadm: reject a node joining the cluster if a node with the same name already exists ([#81056](https://github.com/kubernetes/kubernetes/pull/81056), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

## API Changes
- CustomResourceDefinitions now validate documented API semantics of `x-kubernetes-list-type` and `x-kubernetes-map-type` atomic to reject non-atomic sub-types. ([#84722](https://github.com/kubernetes/kubernetes/pull/84722), [@sttts](https://github.com/sttts))

* kubelets are no longer allowed to delete their own Node API object. Prior to 1.11, in rare circumstances related to cloudprovider node ID changes, kubelets would attempt to delete/recreate their Node object at startup. Kubelets older than 1.11 are not supported running against a v1.13+ API server. If an unsupported legacy kubelet encounters this situation, a cluster admin can remove the Node object: ([#71021](https://github.com/kubernetes/kubernetes/pull/71021), [@liggitt](htt...

- Kubectl describe namespace now shows Conditions (#106219, @dlipovetsky) [SIG CLI]

* If the `TokenRequestProjection` feature gate is disabled, projected serviceAccountToken volume sources are now dropped at object creation time, or at object update time if the existing object did not have a projected serviceAccountToken volume source. Previously, these would result in validation errors. ([#72714](https://github.com/kubernetes/kubernetes/pull/72714), [@mourya007](https://github.com/mourya007))...

- Added validation to reject Pods using the `PodLevelResources` feature on Windows OS due to lack of support. The API server rejects Pods with Pod-level resources and a `Pod.spec.os.name` targeting Windows. Kubelet on nodes running Windows also rejects Pods with Pod-level resources at admission phase. ([#133046](https://github.com/kubernetes/kubernetes/pull/133046), [@toVersus](https:...

- Adds support for `InterfaceNamePrefix` and `BridgeInterface` as arguments to `--detect-local-mode` option and also introduces a new optional `--pod-interface-name-prefix` and `--pod-bridge-interface` flags to kube-proxy. ([#95400](https://github.com/kubernetes/kubernetes/pull/95400), [@tssurya](https://github.com/tssurya))

### Other notable changes

* Connections from Pods to Services with 0 endpoints will now ICMP reject immediately, rather than blackhole and timeout. ([#72534](https://github.com/kubernetes/kubernetes/pull/72534), [@thockin](https://github.com/thockin))

* The apiserver sends external versioned object to the admission webhooks now. Please update the webhooks to expect admissionReview.spec.object.raw to be serialized external versions of objects.  ([#55127](https://github.com/kubernetes/kubernetes/pull/55127), [@caesarxuchao](https://github.com/caesarxuchao))

For more information, see [#53040](https://github.com/kubernetes/kubernetes/issues/53040).

* Object quotas are not consistently charged or updated. Specifically, the object count quota does not reliably account for uninitialized objects. Some quotas are charged only when an object is initialized. Others are charged when an object is created, whether it is initialized or not. We plan to fix this issue in a future release.