- Added a new `FileKeyRef` field to containers, allowing them to load variables from files by setting this field.
  
  Introduced the `EnvFiles` feature gate to govern activation of this functionality. ([#132626](https://github.com/kubernetes/kubernetes/pull/132626), [@HirazawaUi](https://github.com/HirazawaUi)) [SIG API Machinery, Apps, Node and Testing]

 * kubeadm: The Token-related fields in the `MasterConfiguration` object have now been refactored. Instead of the top-level `.Token`, `.TokenTTL`, `.TokenUsages`, `.TokenGroups` fields, there is now a `BootstrapTokens` slice of `BootstrapToken` objects that support the same features under the `.Token`, `.TTL`, `.Usages`, `.Groups` fields. ([#64408](https://github.com/kubernetes/kubernetes/pull/64408), [@luxas](https://github.com/luxas))...

- Kubeadm: use the `--service-cluster-ip-range` flag to init or use the ServiceSubnet field in the kubeadm config to pass a comma separated list of Service CIDRs....

- 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]

- Server-side apply behavior has been regularized in the case where a field is removed from the applied configuration. Removed fields which have no other owners are deleted from the live object, or reset to their default value if they have one. Safe ownership transfers, such as the transfer of a `replicas` field from a user to an HPA without resetting to the default value are documented in [Transferring Ownership](https://kubernetes.io/do...

a pointer type or type parameter. The unqualified type name acts as the field name.
</p>

<pre>
// A struct with four embedded fields of types T1, *T2, P.T3 and *P.T4
struct {
	T1        // field name is T1
	*T2       // field name is T2
	P.T3      // field name is T3
	*P.T4     // field name is T4
	x, y int  // field names are x and y
}
</pre>

<p>

  * Previously this would cause the command to fail regardless of whether or not the field was present in the object model
  * Now the command will succeed even if the sort-by field is missing from one or more of the objects

  `hostAliases` fields to mark the fields used as keys in those lists as either defaulted
  or required. ([#124553](https://github.com/kubernetes/kubernetes/pull/124553), [@pmalek](https://github.com/pmalek))

  If the `DeclarativeValidation` feature gate is enabled, mismatches with existing validation are reported via metrics.

- The `metadata.clusterName` field is completely removed. This should not have any user-visible impact. ([#109602](https://github.com/kubernetes/kubernetes/pull/109602), [@lavalamp](https://github.com/lavalamp))