- `PodLifecycleSleepAction` is now turned on by default allowing users to create containers with sleep lifecycle action with a duration of zero seconds ([#130621](https://github.com/kubernetes/kubernetes/pull/130621), [@sreeram-venkitesh](https://github.com/sreeram-venkitesh)) [SIG Node]

- In the PriorityLevelConfiguration object, the `nominalConcurrencyShares` field now accepts a zero value in both the `flowcontrol.apiserver.k8s.io/v1` and `flowcontrol.apiserver.k8s.io/v1beta3` APIs.
   ([#123001](https://github.com/kubernetes/kubernetes/pull/123001), [@tkashem](https://github.com/tkashem))

 ([#64792](https://github.com/kubernetes/kubernetes/pull/64792), [@luxas](https://github.com/luxas))

- Allows PreStop lifecycle handler's sleep action to have a zero value ([#127094](https://github.com/kubernetes/kubernetes/pull/127094), [@sreeram-venkitesh](https://github.com/sreeram-venkitesh)) [SIG Apps, Node and Testing]

`apiserver_kube_aggregator_x509_missing_san_total` and `apiserver_webhooks_x509_missing_san_total`. This metric measures a number of connections to webhooks/aggregated API servers that use certificates without Subject Alternative Names. It being non-zero is a warning sign that these connections will stop functioning in the future since Golang is going to deprecate x509 certificate subject Common Names for server hostname verification. ([#95396](https://github.com/kubernetes/kubernetes/pull/95396),...

- Kube-proxy handles Terminating EndpointSlices conditions and enables zero downtime deployments for Services with ExternalTrafficPolicy=Local author: @andrewsykim ([#117718](https://github.com/kubernetes/kubernetes/pull/117718), [@aojea](https://github.com/aojea)) [SIG Network, Testing and Windows]

    * Old behavior:
      * environment variables explicitly whitelisted via --docker-env-metadata-whitelist were exported as `container_env_*=*`. Default is zero so by default non were exported
      * all docker labels were exported as `container_label_*=*`
    * New behavior:
      * Only `container_name`, `pod_name`, `namespace`, `id`, `image`, and `name` labels are exposed

* When HPAScaleToZero feature gate is enabled HPA supports scaling to zero pods based on object or external metrics. HPA remains active as long as at least one metric value available. ([#74526](https://github.com/kubernetes/kubernetes/pull/74526), [@DXist](https://github.com/DXist))
    * To downgrade the cluster to version that does not support scale-to-zero feature:

* Fixes an HPA-related panic due to division-by-zero. ([#39694](https://github.com/kubernetes/kubernetes/pull/39694), [@DirectXMan12](https://github.com/DirectXMan12))

### Certificates

* Change CollisionCount from int64 to int32 across controllers ([#50575](https://github.com/kubernetes/kubernetes/pull/50575), [@dixudx](https://github.com/dixudx))
* fix GPU resource validation that incorrectly allows zero limits ([#50218](https://github.com/kubernetes/kubernetes/pull/50218), [@dixudx](https://github.com/dixudx))