- The issuer of the certificate is unknown (x509.UnknownAuthorityError)
  - The requested name does not match the set of authorized names (x509.HostnameError)

 - `ServiceNodeExclusion`, `NodeDisruptionExclusion` and `LegacyNodeRoleBehavior` features...

- kube-proxy: a configuration file specified via `--config` is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. ([#82927](https://github.com/kubernetes/kubernetes/pull/82927), [@obitech](https...

- Fixed a bug that prevents kubectl to validate CRDs with schema using x-kubernetes-preserve-unknown-fields on object fields.
  Fix kubectl SchemaError on CRDs with schema using x-kubernetes-preserve-unknown-fields on array types. ([#96563](https://github.com/kubernetes/kubernetes/pull/96563), [@gautierdelorme](https://github.com/gautierdelorme)) [SIG API Machinery and Testing]

  - The issuer of the certificate is unknown (x509.UnknownAuthorityError)
  - The requested name does not match the set of authorized names (x509.HostnameError)

- kubectl
  - The `kubectl convert` command is deprecated and will be removed in a future release ([#70820](https://github.com/kubernetes/kubernetes/pull/70820), [@seans3](https://github.com/seans3))

### Promoted Server Side Unknown Field Validation to Beta

Promoted the `ServerSideFieldValidation` feature gate to beta (on by default). This allows optionally triggering schema validation on the API server that errors when unknown fields are detected. This allows the removal of client-side validation from kubectl while maintaining the same core functionality of erroring out on requests that contain unknown or invalid fields.

* Fixes a bug in openapi published for custom resources using x-kubernetes-preserve-unknown-fields extensions, so that kubectl will allow sending unknown fields for that portion of the object. ([#79636](https://github.com/kubernetes/kubernetes/pull/79636), [@liggitt](https://github.com/liggitt))

- Fixed a bug that prevents kubectl to validate CRDs with schema using x-kubernetes-preserve-unknown-fields on object fields.
  Fix kubectl SchemaError on CRDs with schema using x-kubernetes-preserve-unknown-fields on array types. ([#96562](https://github.com/kubernetes/kubernetes/pull/96562), [@gautierdelorme](https://github.com/gautierdelorme)) [SIG API Machinery and Testing]

- Kubeadm: improve the strict parsing of user YAML/JSON configuration files. Next to printing warnings for unknown and duplicate fields (current state), also print warnings for fields with incorrect case sensitivity - e.g. `controlPlaneEndpoint` (valid), `ControlPlaneEndpoint` (invalid). Instead of only printing warnings during `init` and `join` also print warnings...