- Fixed an issue related to not draining all the pods in a namespace when an empty selector, i.e., "{}," is specified in a Pod Disruption Budget (PDB). ([#119732](https://github.com/kubernetes/kubernetes/pull/119732), [@sairameshv](https://github.com/sairameshv))

    that need to run prior to the network being ready.
* **Enhance Kubelet QoS**:
  * Pods are placed under a new cgroup hierarchy by default. This feature requires
    draining and restarting the node as part of upgrades. To opt-out set
    `--cgroups-per-qos=false`.
  * If `kube-reserved` and/or `system-reserved` are specified, node allocatable

- 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)) [SIG Node]