* Custom apiservers built with the latest apiserver library will have the 100MB limit on the body of resource requests as well. The limit can be altered via ServerRunOptions.MaxRequestBodyBytes.
    * The body size limit does not apply to subresources like pods/proxy that proxy request content to another server.

- The etcd client library vendored in v1.16 (github.com/coreos/etcd/clientv3) has a bug where IPv6 IP addresses get incorrectly trimmed to the first occurance of the `:` character. This affects all users of the client library including the kube-apiserver and kubeadm. We are targeting the fix for this bug in v1.16.3. ([#83550](https://github.com/kubernetes/kubernetes/issues/83550))...

 `http_request_size_bytes_count`
 `http_requests_total, http_response_size_bytes`
 `http_response_size_bytes_sum`
 `http_response_size_bytes_count`
 due to removal from the prometheus client library. Prometheus http request meta-metrics are now generated from [`promhttp.InstrumentMetricHandler`](https://godoc.org/github.com/prometheus/client_golang/prometheus/promhttp#InstrumentMetricHandler) instead.

SIG Instrumentation standardized the structure of log messages and references to Kubernetes objects. Structured logging makes parsing, processing, storing, querying and analyzing logs easier. New methods in the klog library enforce log message structure.

### EndpointSlices are now enabled by default

- Moved `non-graceful node` shutdown to GA. ([#118228](https://github.com/kubernetes/kubernetes/pull/118228), [@carlory](https://github.com/carlory))
- New CEL Library functions to support Kubernetes Quantities. ([#118803](https://github.com/kubernetes/kubernetes/pull/118803), [@alexzielenski](https://github.com/alexzielenski)) [SIG API Machinery]

- AzureFile and CephFS use the new Mount library that prevents logging of sensitive mount options. ([#88684](https://github.com/kubernetes/kubernetes/pull/88684), [@saad-ali](https://github.com/saad-ali)) [SIG Storage]

* Correctly handle transient connection reset errors on GET requests from client library. ([#58520](https://github.com/kubernetes/kubernetes/pull/58520), [@porridge](https://github.com/porridge))

    * For custom apiservers they uses the generic registry in the apiserver library, they get this behavior automatically.
* Expose CSI volume stats via kubelet volume metrics ([#76188](https://github.com/kubernetes/kubernetes/pull/76188), [@humblec](https://github.com/humblec))

* Update Calico version to v2.6.6 ([#58482](https://github.com/kubernetes/kubernetes/pull/58482), [@tmjd](https://github.com/tmjd))
* Correctly handle transient connection reset errors on GET requests from client library. ([#58520](https://github.com/kubernetes/kubernetes/pull/58520), [@porridge](https://github.com/porridge))

- Shared informers now correctly propagate whether they are synced or not. Individual informer handlers may now check if they are synced or not (new `HasSynced` method). Library support is added to assist controllers in tracking whether their own work is completed for items in the initial list (`AsyncTracker`). ([#113985](https://github.com/kubernetes/kubernetes/pull/113985), [@lavalamp](https://github.com/lavalamp))