([#121983](https://github.com/kubernetes/kubernetes/pull/121983), [@andyzhangx](https://github.com/andyzhangx))
- Client-go: Optimized leaders renewing leases by updating leader lock optimistically without getting the record from the API server first. Also, a new metric `leader_election_slowpath_total` was added to allow users to monitor how many leader elections are updated non-optimistically.

* kubectl help now provides "Did you mean this?" suggestions for typo/invalid command names. ([#27049](https://github.com/kubernetes/kubernetes/pull/27049), [@andreykurilin](https://github.com/andreykurilin))
* Lock all possible kubecfg files at the beginning of ModifyConfig. ([#28232](https://github.com/kubernetes/kubernetes/pull/28232), [@cjcullen](https://github.com/cjcullen))