- Kubeadm: Some text in the `kubeadm upgrade plan` output has changed. If you have scripts or other automation that parses this output, please review these changes and update your scripts to account for the new output. ([#98728](https://github.com/kubernetes/kubernetes/pull/98728), [@stmcginnis](https://github.com/stmcginnis)) [SIG Cluster Lifecycle]

reduces the throughput of pod execution and creates user-visible warnings - [future versions of Kubernetes will minimize the likelihood users see pod failures due to this issue](https://github.com/kubernetes/kubernetes/issues/106884). In general, any automation that creates pods [must take Kubelet rejections into account](https://kubernetes.io/docs/concepts/scheduling-eviction/#pod-disruption), and should be designed to retry and backoff where necessary.

### Etcd v3.5.[0-2] data corruption...

imestamp_seconds`, `apiserver_encryption_config_controller_automatic_reload_failures_total`, `apiserver_encryption_config_controller_automatic_reload_success_total`, `apiserver_encryption_config_controller_automatic_reload_last_timestamp_seconds`.
  
  Fixed bug to surface events for the following metrics: `apiserver_encryption_config_controller_automatic_reload_failures_total`, `apiserver_encryption_config_controller_automatic_reload_last_timestamp_seconds`, `apiserver_encryption_conf...

  
  - `apiserver_encryption_config_controller_automatic_reload_failures_total`: Total number of failed automatic reloads of encryption configuration.
  - `apiserver_encryption_config_controller_automatic_reload_success_total`: Total number of successful automatic reloads of encryption configuration.

* iSCSI sessions managed by kubernetes will now explicitly set startup.mode to 'manual' to  prevent automatic login after node failure recovery. This is the default open-iscsi mode, so this change will only impact users who have changed their startup.mode to be 'automatic' in /etc/iscsi/iscsid.conf. ([#57475](https://github.com/kubernetes/kubernetes/pull/57475), [@stmcginnis](https://github.com/stmcginnis))

- KMS: added validation for duplicate kms config name when auto reload is enabled. If you enabled automatic reload of encryption configuration with API server flag `--encryption-provider-config-automatic-reload`, ensure all the KMS provider names (v1 and v2) in the encryption configuration are unique. ([#113697](https://github.com/kubernetes/kubernetes/pull/113697), [@aramase](https://github.com/aramase))...

## Urgent Upgrade Notes
### (No, really, you MUST read this before you upgrade)
#### Cluster Lifecycle
- Kubeadm: add a new `kubelet-finalize` phase as part of the `init` workflow and an experimental sub-phase to enable automatic kubelet client certificate rotation on primary control-plane nodes.

        Item(name="Plumbus", price=32.0),
    ]
```

FastAPI will use the return type annotation to perform:

* Data validation
* Automatic documentation
    * It could power automatic client generators
* **Data filtering**

Before this version it was only supported via the `response_model` parameter.

* kubeadm: preflight checks on external etcd certificates are now skipped when joining a control-plane node with automatic copy of cluster certificates (--certificate-key) ([#75847](https://github.com/kubernetes/kubernetes/pull/75847), [@fabriziopandini](https://github.com/fabriziopandini))

- Kube-proxy: Added dual-stack IPv4/IPv6 support to the iptables proxier. ([#82462](https://github.com/kubernetes/kubernetes/pull/82462), [@vllry](https://github.com/vllry)) [SIG Network]
- Kubeadm now supports automatic calculations of dual-stack node cidr masks to kube-controller-manager. ([#85609](https://github.com/kubernetes/kubernetes/pull/85609), [@Arvinderpal](https://github.com/Arvinderpal)) [SIG Cluster Lifecycle]