- Simplied validation error message for invalid fields by removing redundant field name. ([#132513](https://github.com/kubernetes/kubernetes/pull/132513), [@xiaoweim](https://github.com/xiaoweim)) [SIG API Machinery, Apps, Auth, Node and Scheduling]

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

- The `kubectl diff` changed to ignore managed fields by default, and a new --show-managed-fields flag has been added to allow you to include managed fields in the diff. ([#111319](https://github.com/kubernetes/kubernetes/pull/111319), [@brianpursley](https://github.com/brianpursley))

- Fixes a 1.30.0 regression in openapi descriptions of imagePullSecrets and hostAliases fields to mark the fields used as keys in those lists as either defaulted or required. ([#124694](https://gith...

* ACTION REQUIRED: The Node.Status.Volumes.Attached.DevicePath field is now unset for CSI volumes. Update any external controllers that depend on this field. ([#75799](https://github.com/kubernetes/kubernetes/pull/75799), [@msau42](https://github.com/msau42))...

- Add Probe-level terminationGracePeriodSeconds field ([#99375](https://github.com/kubernetes/kubernetes/pull/99375), [@ehashman](https://github.com/ehashman)) [SIG API Machinery, Apps, Node and Testing]

- Added etcd_object_count metrics for CustomResources. ([#65983](https://github.com/kubernetes/kubernetes/pull/65983), [@sttts](https://github.com/sttts))
- The OpenAPI version field will now be properly autopopulated without needing other OpenAPI fields present in generic API server code. ([#66411](https://github.com/kubernetes/kubernetes/pull/66411), [@DirectXMan12](https://github.com/DirectXMan12))

- 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...

### Other notable changes

  - true/strict - perform validation and error the request on any invalid fields in the ojbect. It will attempt to perform server-side validation if it is enabled on the apiserver, otherwise it will fall back to client-side validation.
  - warn - perform server-side validation and warn on any invalid fields (but ultimately let the request succeed by dropping any invalid fields from the object). If validation is not available on the server, perform no validation.