- 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))

kube-controller-manager, kube-proxy, kubeadm {alpha|config|token|version}, kubemark. Flags should be prefixed with a single dash "-" (0x45) for short form or double dash "--" for long form. Before this change, malformed flags (for example, starting with a non-ascii dash character such as 0x8211: "–") would have been silently treated as positional arguments and ignored. ([#91349](https://github.com/kubernetes/kubernetes/pull/91349), [@neolit123](https://github.com/neolit123)) [SIG API Machinery, Cloud Provider,...