### Other notable changes

- Creation of new `CronJob` objects containing `TZ` or `CRON_TZ` in `.spec.schedule`, accidentally enabled in `v1.22`, is now disallowed. Use the `.spec.timeZone` field instead, supported in `v1.25+` clusters in default configurations. See https://kubernetes.io/docs/concepts/workloads/controllers/cron-jobs/#unsupported-timezone-specification for more information. ([#116252](http...

### Other notable changes

- The `NodeConfiguration` kind in the kubeadm v1alpha2 API has been renamed `JoinConfiguration`...

<p>
Implementation restriction: For compatibility with other tools, a
compiler may disallow the NUL character (U+0000) in the source text.
</p>
<p>
Implementation restriction: For compatibility with other tools, a
compiler may ignore a UTF-8-encoded byte order mark
(U+FEFF) if it is the first Unicode code point in the source text.
A byte order mark may be disallowed anywhere else in the source.
</p>

<h3 id="Characters">Characters</h3>

  - `spec.versions[*].schema.openAPIV3Schema` is now required when creating v1 CustomResourceDefinitions
  - `spec.preserveUnknownFields: true` is disallowed when creating v1 CustomResourceDefinitions; it must be specified within schema definitions as `x-kubernetes-preserve-unknown-fields: true`

- Disallowed label values will show up as "unexpected" in all system components' metrics.
   ([#128100](https://github.com/kubernetes/kubernetes/pull/128100), [@yongruilin](https://github.com/yongruilin)) [SIG Architecture and Instrumentation]

### Other notable changes

        * `[*.]kubelet.kubernetes.io/*`
        * `[*.]node.kubernetes.io/*`
    * Setting other `kubernetes.io/`- and `k8s.io/`-prefixed labels using the `--node-labels` flag will produce a warning in v1.13, and be disallowed in v1.15. Setting labels that are not prefixed with `kubernetes.io/` or `k8s.io/` is still permitted.

* Access to externally managed IP addresses via the kube-apiserver service proxy subresource is no longer allowed by default. This can be re-enabled via the `ServiceProxyAllowExternalIPs` feature gate, but will be disallowed completely in 1.11 ([#57265](https://github.com/kubernetes/kubernetes/pull/57265), [@brendandburns](https://github.com/brendandburns))