- K8s docker config json secrets are now compatible with docker config desktop authentication credentials files ([#82148](https://github.com/kubernetes/kubernetes/pull/82148), [@bbourbie](https://github.com/bbourbie))
- Kubelet and aggregated API servers now use v1 TokenReview and SubjectAccessReview endpoints to check authentication/authorization. ([#84768](https://github.com/kubernetes/kubernetes/pull/84768), [@liggitt](https://github.com/liggitt))

- The `RemoteRequestHeaderUID` feature moves to beta and is now enabled by default. This makes the kube-apiserver propagate UIDs in the `X-Remote-Uid` header in requests to the aggregated API servers. The header is not honored by default for incoming requests, but that can be enabled by setting the `--requestheader-uid-headers` flag explicitly. ([#130560](https://github.com/kubernetes/kubernetes/pull/130560), [@stlaz](https://github.com/stlaz))...

- Added: Log Line for Debugging possible merge errors for kubelet related Config requests. ([#124389](https://github.com/kubernetes/kubernetes/pull/124389), [@holgerson97](https://github.com/holgerson97))
- Aggregated Discovery v2beta1 fixture is removed in `./api/discovery`. Please use v2 ([#127008](https://github.com/kubernetes/kubernetes/pull/127008), [@Jefftree](https://github.com/Jefftree)) [SIG API Machinery]

- Fixed an issue that prevents the linking of trace spans for requests that are proxied through kube-aggregator. ([#124189](https://github.com/kubernetes/kubernetes/pull/124189), [@toddtreece](https://github.com/toddtreece))