Summary: SIG-etcd has patched another potential issue blocking upgrades from v3.5 to v3.6. If you are upgrading, make sure to update to v3.5.26 or later first.
Issue Summary
Recently, the etcd community addressed an issue that may appear when users upgrade from v3.5 to v3.6. This bug can cause the cluster to report “zombie members”, which are etcd nodes that were removed from the database cluster some time ago, and are re-appearing and joining database consensus. The etcd cluster is then inoperable until these zombie members are removed.