- Kubeadm: modified the etcd static Pod `liveness` and `readiness` probes to use a new etcd `v3.5.3+` HTTP(s) health check endpoint `/health?serializable=true` that allows to track the health of individual etcd members and not fail all members if a single member is not healthy in the etcd cluster. ([#110072](https://github.com/kubernetes/kubernetes/pull/110072), [@neolit123](https://github.com/neolit123))

- Added a new Priority and Fairness metric `apiserver_flowcontrol_request_dispatch_no_accommodation_total` to track the number of times a request dispatch attempt results in a no-accommodation status due to lack of available seats. ([#106629](https://github.com/kubernetes/kubernetes/pull/106629), [@tkashem](https://github.com/tkashem))

- Track the number of Pods with a Ready condition in Job status. The feature is alpha and needs the feature gate JobReadyPods to be enabled. ([#104915](https://github.com/kubernetes/kubernetes/pull/104915), [@alculquicondor](https://github.com/alculquicondor))...

### EndpointSlices are now enabled by default

EndpointSlices are an exciting new API that provides a scalable and extensible alternative to the Endpoints API. EndpointSlices track IP addresses, ports, readiness, and topology information for Pods backing a Service.

- Add a `serving` and `terminating` condition to the EndpointSlice API.
  `serving` tracks the readiness of endpoints regardless of their terminating state. This is distinct from `ready` since `ready` is only true when pods are not terminating. 

- kubeadm: enable secure serving for the kube-scheduler ([#80951](https://github.com/kubernetes/kubernetes/pull/80951), [@neolit123](https://github.com/neolit123))
- kubeadm: print the stack trace of an error for klog level `--v>=5` ([#80937](https://github.com/kubernetes/kubernetes/pull/80937), [@neolit123](https://github.com/neolit123))

- Added feature gate `MutatingAdmissionPolicy` for enabling mutation policy in admission chain. ([#123425](https://github.com/kubernetes/kubernetes/pull/123425), [@cici37](https://github.com/cici37))
- Added kubelet metrics to track the memory manager allocation and pinning. ([#121778](https://github.com/kubernetes/kubernetes/pull/121778), [@Tal-or](https://github.com/Tal-or))

## API Changes

- [CRI] Added a new field called `runtime_handler` into `PodSandbox` and `PodSandboxStatus` to track the `RuntimeClass` information of a pod. ([#73833](https://github.com/kubernetes/kubernetes/pull/73833), [@haiyanmeng](https://github.com/haiyanmeng))

## Detailed Bug Fixes And Changes

### API Machinery

- Added `kubernetes_feature_enabled` metric series to track whether each active feature gate is enabled. ([#112690](https://github.com/kubernetes/kubernetes/pull/112690), [@logicalhan](https://github.com/logicalhan))

* no ([#75820](https://github.com/kubernetes/kubernetes/pull/75820), [@YoubingLi](https://github.com/YoubingLi))
* Use stdlib to log stack trace when a panic occurs ([#75853](https://github.com/kubernetes/kubernetes/pull/75853), [@roycaihw](https://github.com/roycaihw))