- Introduced a new declarative validation tag `+k8s:customUnique` to control listmap uniqueness. ([#134279](https://github.com/kubernetes/kubernetes/pull/134279), [@yongruilin](https://github.com/yongruilin)) [SIG API Machinery and Auth]

SIG Storage also moves support for Block Volumes to beta (introduced as alpha in v1.9) and support for Topology Aware Volume Scheduling to stable (introduced as alpha in v1.9 and promoted to beta in 1.10).

### SIG UI

- Introduced API type `coordination.k8s.io/v1beta1/LeaseCandidate`
  `CoordinatedLeaderElection` feature moves to Beta ([#130751](https://github.com/kubernetes/kubernetes/pull/130751), [@Jefftree](https://github.com/Jefftree)) [SIG API Machinery, Etcd and Testing]

* Fixed missing error checking that could cause kubelet to crash in a race condition. ([#60962](https://github.com/kubernetes/kubernetes/pull/60962), [@technicianted](https://github.com/technicianted))
* Introduced `--http2-max-streams-per-connection` command line flag on api-servers and set default to 1000 for aggregated API servers. ([#60054](https://github.com/kubernetes/kubernetes/pull/60054), [@MikeSpreitzer](https://github.com/MikeSpreitzer))

- Fixed the regression that introduced 34s timeout for DELETECOLLECTION calls ([#115341](https://github.com/kubernetes/kubernetes/pull/115341), [@tkashem](https://github.com/tkashem))
- Fixed two regressions introduced by the `PodDisruptionConditions` feature (on by default in 1.26):

    - [Promoted Server Side Unknown Field Validation to Beta](#promoted-server-side-unknown-field-validation-to-beta)
    - [Introduced KMS v2](#introduced-kms-v2)
    - [Kube-proxy images are now based on distroless images](#kube-proxy-images-are-now-based-on-distroless-images)
  - [Known Issues](#known-issues)

- Introduced new apiserver metric `apiserver_flowcontrol_current_inqueue_seats`. This metric is analogous to `apiserver_flowcontrol_current_inqueue_requests`, but tracks the total number of seats, as each request can take more than one seat. ([#119385](https://github.com/kubernetes/kubernetes/pull/119385), [@andrewsykim](https://github.com/andrewsykim))

- Introduced OpenAPI format support for `k8s-short-name` and `k8s-long-name` in CustomResourceDefinition schemas. ([#132504](https://github.com/kubernetes/kubernetes/pull/132504), [@jpbetz](https://github.com/jpbetz)) [SIG API Machinery, Architecture, Auth, CLI, Cloud Provider, Cluster Lifecycle, Instrumentation, Network, Node, Scheduling and Storage]

- Introduce alpha support for exec-based container registry credential provider plugins in the kubelet. ([#94196](https://github.com/kubernetes/kubernetes/pull/94196), [@andrewsykim](https://github.com/andrewsykim)) [SIG Node and Release]

- Resolve a regression introduced in version 1.31 on Windows Proxy, where the creation of HNS endpoints fails if remote HNS endpoints with the same IP address have already been created. ([#131428](https://github.com/kubernetes/kubernetes/pull/131428), [@princepereira](https://g...