- Added the `DetectCacheInconsistency` feature gate, allowing the API server to periodically verify consistency between its `cache` and `etcd`. Detected inconsistencies reported via the `apiserver_storage_consistency_checks_total` metric and trigger purging of affected cache snapshots. ([#132884](https://github.com/kubernetes/kubernetes/pull/132884),...

#### Garbage Collector
* The garbage collector now supports custom APIs added via Custom Resource Definitions
  or aggregated API servers. The garbage collector controller refreshes periodically.
  Therefore, expect a latency of about 30 seconds between when an API is added and when
  the garbage collector starts to manage it.


#### Monitoring/Prometheus

* Kubelet: replace `du` and `find` with a golang implementation ([#74675](https://github.com/kubernetes/kubernetes/pull/74675), [@dashpole](https://github.com/dashpole))
    * Kubelet: periodically update machine info to support hot-add/remove

* Fix log spam due to unnecessary status update when node is deleted. ([#45923](https://github.com/kubernetes/kubernetes/pull/45923), [@verult](https://github.com/verult))
* Poll all active pods periodically for volumes to fix out of order pod & node addition events. Fixes volumes not getting detached after controller restart. ([#42033](https://github.com/kubernetes/kubernetes/pull/42033), [@NickrenREN](https://github.com/NickrenREN))

  - Clients should reload the token from disk periodically (once per minute is recommended) to ensure they continue to use a valid token. `k8s.io/client-go` version v11.0.0+ and v0.15.0+ reload tokens automatically.

- Try to send watch bookmarks (if requested) periodically in addition to sending them right before timeout ([#90560](https://github.com/kubernetes/kubernetes/pull/90560), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]

### Misc

- Service account controller clients to now use the TokenRequest API, and tokens are periodically rotated. ([#72179](https://github.com/kubernetes/kubernetes/pull/72179), [@WanLinghao](https://github.com/WanLinghao))

* Fix CVE-2019-11247: API server allows access to custom resources via wrong scope ([#80750](https://github.com/kubernetes/kubernetes/pull/80750), [@sttts](https://github.com/sttts))
* Failed iscsi logout is now re-tried periodically. ([#78941](https://github.com/kubernetes/kubernetes/pull/78941), [@jsafrane](https://github.com/jsafrane))

### Introducing Graceful Node Shutdown (Alpha)