- Fixed a bug where an API group's path was not unregistered from the API server's root paths when the group was deleted. ([#121283](https://github.com/kubernetes/kubernetes/pull/121283), [@tnqn](https://github.com/tnqn)) [SIG API Machinery and Testing]

## Changelog since v1.18.15

## Changes by Kind

### Bug or Regression

- Avoid marking node as Ready until node has synced with API servers at least once ([#99034](https://github.com/kubernetes/kubernetes/pull/99034), [@ehashman](https://github.com/ehashman)) [SIG Node]

 *
 * Usually a webserver is reachable with multiple identifiers: its IP addresses, registered
 * domain names, and even `localhost` when connecting from the server itself. Each of a web server's
 * names is a distinct URL and they are not interchangeable. For example, even if
 * `http://square.github.io/dagger` and `http://google.github.io/dagger` are served by the same IP

- The API server's encryption at rest configuration now allows the use of wildcards in the list of resources.  For example, '*.*' can be used to encrypt all resources, including all current and future custom resources. ([#115149](https://github.com/kubernetes/kube...

- Kube-apiserver: redirects from backend API servers are no longer followed when checking availability with requests to `/apis/$group/$version` ([#112772](https://github.com/kubernetes/kubernetes/pull/112772), [@liggitt](https://github.com/liggitt)) [SIG API Machinery and Testing]

* Fix a bug in server printer that could cause kube-apiserver to panic. ([#79349](https://github.com/kubernetes/kubernetes/pull/79349), [@roycaihw](https://github.com/roycaihw))
* Fix a bug in the IPVS proxier where virtual servers are not cleaned up even though the corresponding Service object was deleted. ([#80942](https://github.com/kubernetes/kubernetes/pull/80942), [@gongguan](https://github.com/gongguan))

  
  Multi vCenter support is deprecated as of v1.21. If you have a Kubernetes cluster spanning across multiple vCenter servers, please consider moving all k8s nodes to a single vCenter Server. vSphere CSI Driver does not support Kubernetes deployment spanning across multiple vCenter servers.
  

- API priority and fairness graduated to beta. 1.19 servers with APF turned on should not be run in a multi-server cluster with 1.20+ servers. ([#96527](https://github.com/kubernetes/kubernetes/pull/96527), [@adtac](https://github.com/adtac)) [SIG API Machinery and Testing]

    * In a future...

* Auto-generate a "server" in OpenAPI `servers` when there's a `root_path` instead of prefixing all the `paths`:
    * Add a new parameter for `FastAPI` classes: `root_path_in_servers` to disable the auto-generation of `servers`.
    * New docs about `root_path` and `servers` in [Additional Servers](https://fastapi.tiangolo.com/advanced/behind-a-proxy/#additional-servers).