* kube-apiserver: the OpenID Connect authenticator can now verify ID Tokens signed with JOSE algorithms other than RS256 through the --oidc-signing-algs flag. ([#58544](https://github.com/kubernetes/kubernetes/pull/58544), [@ericchiang](https://github.com/ericchiang))

* The OpenID Connect authenticator can now use a custom prefix, or omit the default prefix, for username and groups claims through the --oidc-username-prefix and --oidc-groups-prefix flags. For example, the authenticator can map a user with the username "jane" to "google:jane"...

* API server authentication now caches successful bearer token authentication results for a few seconds. ([#50258](https://github.com/kubernetes/kubernetes/pull/50258), [@liggitt](https://github.com/liggitt))

### API Change

- Fixed issue where `kubectl-convert` would fail when encountering resources that could not be converted to the specified api version. New behavior is to warn the user of the failed conversions and continue to convert the remaining resources. ([#117002](https://github.com/kubernetes/kubernetes/pull/117002), [@gxwilkerson33](https://github.com/gxwilkerson33))

- Fixes a regression in v1beta1 PodDisruptionBudget handling of `strategic merge patch`-type API requests for the `selector` field. Prior to 1.21, these requests would merge `matchLabels` content and replace `matchExpressions` content. In 1.21, patch requests touching the `selector` field started replacing the entire selector. This is consistent with server-side apply and the v1 PodDisruptionBudget behavior, but should not have been changed for v1beta1. ([#...

- Ignore context canceled from validate and mutate webhook ([#120017](https://github.com/kubernetes/kubernetes/pull/120017), [@divyasri537](https://github.com/divyasri537)) [SIG API Machinery]

### API Change

- Signatures on scale client methods have been modified to accept `context.Context` as a first argument. Signatures of Get, Update, and Patch methods have been updated to accept GetOptions, UpdateOptions and PatchOptions respectively. ([#88599](https://github.com/kubernetes/kubernetes/pull/88599), [@julianvmodesto](https://...

### Auth

- Fixed OpenID Connect (OIDC) token refresh when the client secret contains a special character. ([#76914](https://github.com/kubernetes/kubernetes/pull/76914), [@tsuna](https://github.com/tsuna))