- Dropped support for `certificates/v1beta1` `CertificateSigningRequest` in `kubectl`. ([#134782](https://github.com/kubernetes/kubernetes/pull/134782), [@scaliby](https://github.com/scaliby))
- Dropped support for `discovery/v1beta1` `EndpointSlice` in `kubectl`. ([#134913](https://github.com/kubernetes/kubernetes/pull/134913), [@scaliby](https://github.com/scaliby))

    - `apps/v1beta1=true`
    - `apps/v1beta2=true`
    - `extensions/v1beta1/daemonsets=true,extensions/v1beta1/deployments=true,extensions/v1beta1/replicasets=true,extensions/v1beta1/networkpolicies=true,extensions/v1beta1/podsecuritypolicies=true`

* For Deployment, ReplicaSet, and DaemonSet, selectors are now immutable when updating via the new `apps/v1beta2` API. For backward compatibility, selectors can still be changed when updating via `apps/v1beta1` or `extensions/v1beta1`. ([#50719](https://github.com/kubernetes/kubernetes/pull/50719), [@crimsonfaith91](https://github.com/crimsonfaith91))

- 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]

- Introduced the `admissionregistration.k8s.io/v1beta1/MutatingAdmissionPolicy` API type. To enable, enable the `MutatingAdmissionPolicy` feature gate (which was off by default) and set `--runtime-config=admissionregistration.k8s.io/v1beta1=true` on the kube-apiserver. 

### Bug or Regression

- Kubeadm: fixed bug where v1beta3's ClusterConfiguration.APIServer.TimeoutForControlPlane is not respected in newer versions of kubeadm where v1beta4 is the default. ([#133755](https://github.com/kubernetes/kubernetes/pull/133755), [@HirazawaUi](https://github.com/HirazawaUi)) [SIG Cluster Lifecycle]

  Please use the command "kubeadm config migrate" to migrate your existing v1beta3 configuration to v1beta4.
  
  v1beta3 is now marked as deprecated but will continue to be supported until version 1.34 or later.

- Kube-apiserver: the AuthorizationConfiguration type accepted in `--authorization-config` files has been promoted to `apiserver.config.k8s.io/v1beta1`. ([#123640](https://github.com/kubernetes/kubernetes/pull/123640), [@liggitt](https://github.com/liggitt))...

- The `flowcontrol.apiserver.k8s.io/v1beta3` `FlowSchema` and `PriorityLevelConfiguration` APIs has been promoted to `flowcontrol.apiserver.k8s.io/v1`, with the following changes:

- Kubeadm: removed the deprecated `v1beta2` API. kubeadm 1.26's `config migrate`
  command can be used to migrate a `v1beta2` configuration file to `v1beta3` ([#114540](https://github.com/kubernetes/kubernetes/pull/114540), [@pacoxu](https://github.com/pacoxu))