1.21 is the latest version as of writing.
Our notes: https://wikitech.wikimedia.org/wiki/Portal:Toolforge/Admin/Kubernetes/Upgrading_Kubernetes
Release notes: https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG/CHANGELOG-1.21.md
Highlights:
- PodSecurityPolicy deprecated, need to find a solution before 1.25
- Kustomize updates
- Kubelet structured logging
- cronjobs v1 available (currently v1beta1)