* If the TaintNodesByCondition is enabled, a node will be tainted when it is under PID pressure.  ([#60008](https://github.com/kubernetes/kubernetes/pull/60008), [@k82cn](https://github.com/k82cn))

* The Kubelet Summary API will now include total usage of pods through the "pods" SystemContainer. ([#57802](https://github.com/kubernetes/kubernetes/pull/57802), [@dashpole](https://github.com/dashpole))

- 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. ([#87461](https://github.com/kubernetes/kubernetes/pull/87461), [@bboreham](https://github.com/bboreham))...

- In clusters where the DryRun feature...

* StatefulSets now include an alpha scaling feature accessible by setting the `spec.podManagementPolicy` field to `Parallel`.  The controller will not wait for pods to be ready before adding the other pods, and will replace deleted pods as needed.  Since parallel scaling creates pods out of order, you cannot depend on predictable membership changes within your set. ([#44899](https://github.com/kubernetes/kubernetes/pull/44899), [@smarterclayton](https://github.com/smarterclayton))...

- Static pods were taking extra time to be restarted after being updated.  Static pods that are waiting to restart were not correctly counted in `kubelet_working_pods`. ([#116995](https://github.com/kubernetes/kubernetes/pull/116995), [@smarterclayton](https://github.com/smarterclayton)) [SIG Node]

- `kubectl run` has removed the previously deprecated generators, along with flags unrelated to creating pods. `kubectl run` now only creates pods. See specific `kubectl create` subcommands to create objects other than pods. 
([#87077](https://github.com/kubernetes/kubernetes/pull/87077), [@soltysh](https://github.com/soltysh)) [SIG Architecture, CLI and Testing]

- Critical pods can now be created in namespaces other than kube-system. To limit critical pods to the kube-system namespace, cluster admins should create an admission configuration file limiting critical pods by default, and a matching quota object in the `kube-system` namespace permitting critical pods in that namespace. See https://kubernetes.io/docs/concepts/policy/resource-quotas/#limit-priority-clas...

* Improve efficiency of preemption logic in clusters with many pending pods. ([#72895](https://github.com/kubernetes/kubernetes/pull/72895), [@bsalamat](https://github.com/bsalamat))
* Fix scheduling starvation of pods in cluster with large number of unschedulable pods. ([#72619](https://github.com/kubernetes/kubernetes/pull/72619), [@everpeace](https://github.com/everpeace))

- Kubernetes cannot distinguish between GCE Zonal PDs and Regional PDs with the same name. To workaround this issue, precreate PDs with unique names. PDs that are dynamically provisioned do not encounter this issue. ([#70716](https://github.com/kubernetes/kubernetes/pull/70716), [@msau42](https://github.com/msau42))

## Known Issues

### PID Limits graduates to General Availability

PID Limits features are now generally available on both `SupportNodePidsLimit` (node-to-pod PID isolation) and `SupportPodPidsLimit` (ability to limit PIDs per pod), after being enabled-by-default in beta stage for a year.

### API Priority and Fairness graduates to Beta