* Fix kubectl describe for pods with controllerRef  ([#45467](https://github.com/kubernetes/kubernetes/pull/45467), [@ddysher](https://github.com/ddysher))
* Skip errors when unregistering juju kubernetes-workers ([#48144](https://github.com/kubernetes/kubernetes/pull/48144), [@ktsakalozos](https://github.com/ktsakalozos))

- Added '--concurrent-cron-job-syncs' flag for `kube-controller-manager` to set the number of workers for cron job controller. ([#117550](https://github.com/kubernetes/kubernetes/pull/117550), [@borgerli](https://github.com/borgerli))
- Added '--concurrent-job-syncs' flag for `kube-controller-manager` to set the number of job controller workers. ([#117138](https://github.com/kubernetes/kubernetes/pull/117138), [@tosi3k](https://github.com/tosi3k))

- Fixed a data race in the kubelet image manager that can cause static pod workers to silently stop working. ([#88915](https://github.com/kubernetes/kubernetes/pull/88915), [@roycaihw](https://github.com/roycaihw)) [SIG Node]

- Fixed a data race in kubelet image manager that can cause static pod workers to silently stop working. ([#88915](https://github.com/kubernetes/kubernetes/pull/88915), [@roycaihw](https://github.com/roycaihw)) [SIG Node]

- "unfinished_work_microseconds" is added to the workqueue metrics; it can be used to detect stuck worker threads. (kube-controller-manager runs many workqueues.) ([#70884](https://github.com/kubernetes/kubernetes/pull/70884), [@lavalamp](https://github.com/lavalamp))

    * If you are not switching kube-proxy between different modes, this change should not require...

* Use upgraded container-vm by default on worker nodes for GCE k8s clusters ([#31023](https://github.com/kubernetes/kubernetes/pull/31023), [@vishh](https://github.com/vishh))

### Other notable changes

- Added `--concurrent-daemonset-syncs` command line flag to kube-controller-manager. This value sets the number of workers for the daemonset controller. ([#128444](https://github.com/kubernetes/kubernetes/pull/128444), [@tosi3k](https://github.com/tosi3k))

- Flag `--concurrent-node-syncs` has been added to cloud node controller which defines how many workers in parallel will be initialising and synchronising nodes. ([#113104](https://github.com/kubernetes/kubernetes/pull/113104), [@pawbana](https://github.com/pawbana)) [SIG API Machinery, Cloud Provider and Scalability]

- The DownwardAPIHugePages feature is beta.  Users may use the feature if all workers in their cluster are min 1.20 version.  The feature will be enabled by default in all installations in 1.22. ([#99610](https://github.com/kubernetes/kubernetes/pull/99610), [@derekwaynecarr](https://github.com/derekwaynecarr)) [SIG Node]