- Added support for CEL expressions with escaped names in the structured authentication config. Using `[...]` to access claims or user data was recommended when names contained characters that would otherwise need escaping. CEL optionals with `?` could be used where has was not applicable — for example, `claims[?"kubernetes.io"]` or `user.extra[?"domain.io/foo"]`. ([#131574](https://github.com/kubernetes/kubernetes/pull/131574),...

### Failing Test

- Escape the special characters like `[`, `]` and ` ` that exist in vsphere windows path ([#98830](https://github.com/kubernetes/kubernetes/pull/98830), [@liyanhui1228](https://github.com/liyanhui1228)) [SIG Storage and Windows]

- Added a alpha feature, behind the `RelaxedEnvironmentVariableValidation` feature gate.
  When that gate is enabled, Kubernetes allows almost all printable ASCII characters to be used in the names
  of environment variables for containers in Pods. ([#123385](https://github.com/kubernetes/kubernetes/pull/123385), [@HirazawaUi](https://github.com/HirazawaUi))

- In the `kubectl describe` output, the fields with names containing special characters are now displayed as-is without any pretty formatting, avoiding awkward outputs.  ([#75483](https://github.com/kubernetes/kubernetes/pull/75483), [@gsadhani](https://github.com/gsadhani))

- Fixed CSI `PersistentVolumes` to allow Secrets names longer than 63 characters. ([#114776](https://github.com/kubernetes/kubernetes/pull/114776), [@jsafrane](https://github.com/jsafrane))

## Changelog since v1.19.8

## Changes by Kind

### Failing Test

- Fix handing special characters in the volume path on Windows ([#99137](https://github.com/kubernetes/kubernetes/pull/99137), [@yujuhong](https://github.com/yujuhong)) [SIG Storage]

### Bug or Regression

  
  1. `apiGroup`: If set, it must be a valid DNS subdomain (e.g. 'example.com').
  2. `kind` and `name`: It must be valid path segment name. It may not be '.' or '..' and it may not contain '/' and '%' characters. ([#125218](https://github.com/kubernetes/kubernetes/pull/125218), [@carlory](https://github.com/carlory))
- Enabled kubectl to find `kubectl-create-subcommand` plugins when positional

- Limit vSphere volume name to 63 characters long. ([#100404](https://github.com/kubernetes/kubernetes/pull/100404), [@gnufied](https://github.com/gnufied))

- Volume mount cleanup now considers only plugin directory and not the entire kubelet root ([#112607](https://github.com/kubernetes/kubernetes/pull/112607), [@mattcary](https://github.com/mattcary))
- `kubectl` now escapes terminal special characters in output. This fixes CVE-2021-25743.
   ([#112553](https://github.com/kubernetes/kubernetes/pull/112553), [@dgl](https://github.com/dgl))

### Other (Cleanup or Flake)

## Changelog since v1.18.16

## Changes by Kind

### Failing Test

- Fix handing special characters in the volume path on Windows ([#99138](https://github.com/kubernetes/kubernetes/pull/99138), [@yujuhong](https://github.com/yujuhong)) [SIG Storage]

### Bug or Regression