* We eliminate unnecessary node creation by catching cases where old nodes can be reused
       * because their next fields won't change. Statistically, at the default threshold, only
       * about one-sixth of them need cloning when a table doubles. The nodes they replace will be
       * garbage collectable as soon as they are no longer referenced by any reader thread that may
       * be in the midst of traversing table right now.
       */

    For more details, see [Advanced audit](https://kubernetes.io/docs/tasks/debug-application-cluster/audit/#advanced-audit).

* The deprecated `ThirdPartyResource` (TPR) API was removed.
  To avoid losing your TPR data, [migrate to CustomResourceDefinition](https://kubernetes.io/docs/tasks/access-kubernetes-api/migrate-third-party-resource/).

* The following deprecated flags were removed from `kube-controller-manager`:

In particular, the following storage features are moving to GA in Kubernetes 1.18:
- Raw Block Support: Allow volumes to be surfaced as block devices inside containers instead of just mounted filesystems.
- Volume Cloning: Duplicate a PersistentVolumeClaim and underlying storage volume using the Kubernetes API via CSI.
- CSIDriver Kubernetes API Object: Simplifies CSI driver discovery and allows CSI Drivers to customize Kubernetes behavior.

* GCE: Internal load balancer IPs are now reserved during service sync to prevent losing the address to another service. ([#51055](https://github.com/kubernetes/kubernetes/pull/51055), [@nicksardo](https://github.com/nicksardo))