- kube-proxy: a configuration file specified via `--config` is now loaded with strict deserialization, which fails if the config file contains duplicate or unknown fields. This protects against accidentally running with config files that are malformed, mis-indented, or have typos in field names, and getting unexpected behavior. ([...

- Custom resource requests with `fieldValidation=Strict` consistently require `apiVersion` and `kind`, matching non-strict requests ([#109019](https://github.com/kubernetes/kubernetes/pull/109019), [@liggitt](https://github.com/liggitt))

- The getters for the field name and typeDescription of the Reflector struct were renamed. ([#128035](https://github.com/kubernetes/kubernetes/pull/128035), [@alexanderstephan](https://github.com/alexanderstephan)) [SIG API Machinery]

- Added a new option `strict-cpu-reservation` for CPU Manager static policy. When this option is enabled, CPU cores in `reservedSystemCPUs` will be strictly used for system daemons and interrupt processing no longer available for any workload. ([#130290](https://github.com/k...

* [IPVS] Allow for transparent kube-proxy restarts ([#75283](https://github.com/kubernetes/kubernetes/pull/75283), [@lbernail](https://github.com/lbernail))

- Kubernetes is now built using go 1.17. ([#103692](https://github.com/kubernetes/kubernetes/pull/103692), [@justaugustus](https://github.com/justaugustus))
- Performs strict server side schema validation requests via the `fieldValidation=[Strict,Warn,Ignore]`. ([#105916](https://github.com/kubernetes/kubernetes/pull/105916), [@kevindelgado](https://github.com/kevindelgado))
- Promote `IPv6DualStack` feature to stable.

- Added support for a new kubectl output format, `kyaml`. KYAML was a strict subset of YAML and should be accepted by any YAML processor. The formatting of KYAML was halfway between JSON and YAML.  Because it was more explicit than the default YAML style, it was less error-prone. ([#132942](https://github.com/kubernetes/k...

- Adds the ability to pass --strict-transport-security-directives to the kube-apiserver to set the HSTS header appropriately.  Be sure you understand the consequences to browsers before setting this field. ([#96502](https://github.com/kubernetes/kubernetes/pull/96502), [@249043822]...

- Promoted meta.k8s.io/v1beta1 Table and PartialObjectMetadata to v1. ([#77136](https://github.com/kubernetes/kubernetes/pull/77136), [@smarterclayton](https://github.com/smarterclayton))

- Changed how the API server handles updates to `.spec.defaultBackend` of Ingress objects.