* AWS: Handle kube-down case where the LaunchConfig is dangling ([#30816](https://github.com/kubernetes/kubernetes/pull/30816), [@zmerlynn](https://github.com/zmerlynn))
* kubectl will no longer do client-side defaulting on create and replace. ([#30250](https://github.com/kubernetes/kubernetes/pull/30250), [@krousey](https://github.com/krousey))

  fields: ipFamilyPolicy (SingleStack, PreferDualStack, RequireDualStack),
  ipFamilies (a list of families assigned), and clusterIPs (inclusive of
  clusterIP).  Most users do not need to set anything at all, defaulting will
  handle it for them.  Services are single-stack unless the user asks for

- Graduated seccomp profile defaulting to GA.
  
  Set the kubelet `--seccomp-default` flag or `seccompDefault` kubelet configuration field to `true` to make pods on that node default to using the `RuntimeDefault` seccomp profile.
  

### SIG API Machinery

[SIG API Machinery][] is responsible for all aspects of the API server: API registration and discovery, generic API CRUD semantics, admission control, encoding/decoding, conversion, defaulting, persistence layer (etcd), OpenAPI, third-party resources, garbage collection, and client libraries.

* Resolves spurious rollouts of workload controllers when upgrading the API server from 1.11 -> 1.12 due to incorrect defaulting of an alpha procMount field in pods ([#78881](https://github.com/kubernetes/kubernetes/pull/78881), [@liggitt](https://github.com/liggitt))

- Fix the code is leaking the defaulting between unrelated pod instances. ([#103284](https://github.com/kubernetes/kubernetes/pull/103284), [@kebe7jun](https://github.com/kebe7jun)) [SIG CLI]

- Bug: client-go clientset was not defaulting to the user agent, and was using the default golang agent for all the requests. ([#108772](https://github.com/kubernetes/kubernetes/pull/108772), [@aojea](https://github.com/aojea))

## Changelog since v1.11.0

### Action Required

    * installed StorageClass API object. Alternatively, administrators may choose to
    * keep the automatically installed StorageClass and only disable the defaulting
    * behavior by removing the "is-default-class" annotation from the StorageClass
    * API object.

* The RBAC bootstrapping policy now allows authenticated users to create selfsubjectrulesreviews. ([#56095](https://github.com/kubernetes/kubernetes/pull/56095), [@ericchiang](https://github.com/ericchiang))