- The scheduler retries scheduling Pods rejected by PreFilterResult (PreFilter plugins) more appropriately; it now takes events registered in those rejector PreFilter plugins into consideration. ([#122251](https://github.com/kubernetes/kubernetes/pull/122251), [@olderTaoist](https://github.com/olderTaoist)) [SIG Scheduling and Testing]

- The scheduling queue didn't notice any extenders' failures, it could miss some cluster events,
  and it could end up Pods rejected by Extenders stuck in unschedulable pod pool in 5min in the worst-case scenario.
  Now, the scheduling queue notices extenders' failures and requeue Pods rejected by Extenders appropriately. ([#122044](https://github.com/kubernetes/kubernetes/pull/122044), [@sanposhiho](https://github.com/sanposhiho)) [SIG Scheduling]

  - *apiserver_cache_list_fetched_objects_total*: Counter of objects read from watch cache in the course of serving a LIST request, broken down by resource_prefix and index_name
  - *apiserver_cache_list_evaluated_objects_total*: Counter of objects tested in the course of serving a LIST request from watch cache, broken down by resource_prefix

* The `spec.SecurityContext.Sysctls` field is now dropped during creation of `Pod` objects unless the `Sysctls` feature gate is enabled. ([#72752](https://github.com/kubernetes/kubernetes/pull/72752), [@rajathagasthya](https://github.com/rajathagasthya))
    * The `spec.AllowedUnsafeSysctls` and `spec.ForbiddenSysctls` fields are now dropped during creation of `PodSecurityPolicy` objects unless the `Sysctls` feature gate is enabled.

- Kube-scheduler now retries scheduling Pods rejected by the PodTopologySpread plugin when related Pods are created, deleted, updated,...

- Fixes an issue cleaning up CertificateSigningRequest objects with an unparseable `status.certificate` field ([#103948](https://github.com/kubernetes/kubernetes/pull/103948), [@liggitt](https://github.com/liggitt)) [SIG Apps and Auth]

- Fixes an issue cleaning up CertificateSigningRequest objects with an unparseable `status.certificate` field ([#103949](https://github.com/kubernetes/kubernetes/pull/103949), [@liggitt](https://github.com/liggitt)) [SIG Apps and Auth]

### Bug or Regression

- '`metav1.LabelSelectors` specified in API objects are now validated to ensure
  they do not contain invalid label values that will error at time of use. Existing
  invalid objects can be updated, but new objects are required to contain valid
  label selectors.'

  //   allows any non-core object, as well as PersistentVolumeClaim objects.
  // * While dataSource ignores disallowed values (dropping them), dataSourceRef
  //   preserves all values, and generates an error if a disallowed value is
  //   specified.
  // * While dataSource only allows local objects, dataSourceRef allows objects
  //   in any namespaces.