What needs to be done?

Until its release, a preliminary release with suffix -SNAPSHOT is part of the releases. This GitHub release becomes obsolete after successful release.

Suppose a release is built from branch release/2.1.x and the current project version is 2.1.1-SNAPSHOT in the root pom of that branch and a preliminary release 2.1.1-SNAPSHOT exists in the repository, then this release should be deleted as part of the post-release job of the release workflow.