A Tanzu Kubernetes release provides the Kubernetes software distribution signed and supported by VMware for Tanzu Kubernetes clusters provisioned by the Tanzu Kubernetes Grid Service.

Tanzu Kubernetes releases Release Notes

For a list of all Tanzu Kubernetes releases, refer to the release notes.

Verify Tanzu Kubernetes Cluster Compatibility for Update

Before upgrading the vSphere with Tanzu infrastructure, including the vCenter Server and the Supervisor Cluster, refer to the Knowledge Base article https://kb.vmware.com/s/article/82592 for guidance on how to check if any Tanzu Kubernetes clusters are incompatible with the upgrade. If a Tanzu Kubernetes cluster is incompatible with the target infrastructure, upgrade the cluster before proceeding with the system upgrade.

Use Kubectl to List Available Tanzu Kubernetes releases

You can list Tanzu Kubernetes releases and view the compatibility and updatability for each release using following command. 
kubectl get tanzukubernetesreleases
The COMPATIBLE column indicates if that Tanzu Kubernetes release is compatible with the current Supervisor Cluster. The UPDATES AVAILABLE column indicates if there is a Kubernetes upgrade available and the recommended next Tanzu Kubernetes releases to be used. 
NAME                                VERSION                          READY   COMPATIBLE   CREATED   UPDATES AVAILABLE
v1.18.15---vmware.1-tkg.1.600e412   1.18.15+vmware.1-tkg.1.600e412   True    True         21h       [1.19.7+vmware.1-tkg.1.fc82c41]
v1.19.7---vmware.1-tkg.1.fc82c41    1.19.7+vmware.1-tkg.1.fc82c41    True    True         21h       [1.20.2+vmware.1-tkg.1.1d4f79a]
v1.20.2---vmware.1-tkg.1.1d4f79a    1.20.2+vmware.1-tkg.1.1d4f79a    True    True         21h

This same information is also available using kubectl get tkc <tkgs-cluster-name>.