- When registering with a 1.17+ API server, a CustomResourceDefinition conversion webhook can now request that only `v1` ConversionReview requests be sent to them. Previously, conversion webhooks were required to support receiving `v1beta1` ConversionReview requests as well for compatibility...

- Fix a bug where events/v1 Events with similar event type and reporting instance were not aggregated by client-go. ([#112365](https://github.com/kubernetes/kubernetes/pull/112365), [@dgrisonnet](https://github.com/dgrisonnet)) [SIG API Machinery and Instrumentation]

- The fallback behavior of the Downward API's `resourceFieldRef` field was updated to account for pod-level resources: if container-level limits were not set, pod-level limits were now used before falling back to node allocatable resources. ([#132605](https://github.com/kubernetes/kubernetes/pull/132605), [@toVersus](https://github.com/toVersus)) [SIG Node, Scheduling and Testing]

- Kubeadm: Fixed a bug where the PublicKeysECDSA feature gate was not respected when generating kubeconfig files. ([#12538...

- Fixed a suboptimal scheduler preemption behavior where potential preemption victims were violating Pod Disruption Budgets. ([#128307](https://github.com/kubernetes/kubernetes/pull/128307), [@NoicFank](https://github.com/NoicFank)) [SIG Scheduling]
- Fixed an issue in the kubelet that showed when writeable layers and read-only layers were at different paths within the same mount.

* The following deprecated flags were removed from `kube-controller-manager`:

  * `replication-controller-lookup-cache-size`
  * `replicaset-lookup-cache-size`
  * `daemonset-lookup-cache-size`

  Don't use these flags. Using deprecated flags causes the server to print a warning. Using a removed flag causes the server to abort the startup.

* The following deprecated flags were removed from `kubelet`:

- Fixed a bug where the CPU set allocated to an init container, with containerRestartPolicy of `Always`, were erroneously reused by a regular container. ([#119447](https://github.com/kubernetes/kubernetes/pull/119447), [@gjkim42](https://github.com/gjkim42)) [SIG Node and Testing]

   ([#123273](https://github.com/kubernetes/kubernetes/pull/123273),...

  managed by the GLBC Ingress Controller. This can cause the health checks to start failing,
  requiring you to reapply the manual edits.
  * This issue does not affect clusters that were already running Kubernetes v1.6.4 or higher.
  * This issue does not affect Health Checks that were left in the configuration
    [originally set by the GLBC Ingress Controller](https://github.com/kubernetes/ingress-nginx/tree/0.9.0-beta.1/controllers/gce#health-checks).

* Fix a bug in GCE multizonal clusters where PersistentVolumes were sometimes created in zones without nodes. ([#52322](https://github.com/kubernetes/kubernetes/pull/52322), [@davidz627](https://github.com/davidz627))
* Fix validation of NetworkPolicy ([#56223](https://github.com/kubernetes/kubernetes/pull/56223), [@deads2k](https://github.com/deads2k))