- Kubeadm: enhanced the "patches" functionality to be able to patch kubelet config files containing `v1beta1.KubeletConfiguration`. The new patch target is called `kubeletconfiguration` (e.g. patch file `kubeletconfiguration+json.json`).This makes it possible to apply node specific KubeletConfiguration options during `init`, `join` and `upgrade`, while the main `KubeletConfiguration` that is passed to `init` as part of the `--config` file can still act as the global stored in the cluster `KubeletConfiguration`....

- 'kubeadm: Stopped storing the ResolverConfig in the global KubeletConfiguration
  and sets it dynamically for each node instead.' ([#124038](https://github.com/kubernetes/kubernetes/pull/124038), [@SataQiu](https://github.com/SataQiu))
- 'kubeadm: fixed a regression where the KubeletConfiguration is not properly
  downloaded during "kubeadm upgrade" command from the kube-system/kubelet-config

- Kubeadm: fixed a bug on 'kubeadm join' where using patches with a kubeletconfiguration target was not respected when performing the local kubelet healthz check. ([#126251](https://github.com/kubernetes/kubernetes/pull/126251), [@neolit123](https://github.com/neolit123)) [SIG Cluster Lifecycle]

warnings for fields with incorrect case sensitivity - e.g. `controlPlaneEndpoint` (valid), `ControlPlaneEndpoint` (invalid). Instead of only printing warnings during `init` and `join` also print warnings when downloading the ClusterConfiguration, KubeletConfiguration or KubeProxyConfiguration objects from the cluster. This can be useful if the user has patched these objects in their respective ConfigMaps with mistakes. ([#107725](https://github.com/kubernetes/kubernetes/pull/107725), [@neolit123](https...

- kubelet: added `KubeletConfiguration.subidsPerPod`. ([#130028](https://github.com/kubernetes/kubernetes/pull/130028), [@AkihiroSuda](https://github.com/AkihiroSuda)) [SIG API Machinery and Node]

* Fixes a bug with cAdvisorPort in the KubeletConfiguration that prevented setting it to 0, which is in fact a valid option, as noted in issue [#11710](https://github.com/kubernetes/kubernetes/pull/11710). ([#46876](https://github.com/kubernetes/kubernetes/pull/46876), [@mtaufen](https://github.com/mtaufen))...