Our upgrade of GitVersion in November exposed us to this problem, which I just triggered accidentally. GRM considers branches like "support-XXX" to be a mainline branch, like "master" or "main". So when I created a branch named "support-nunit4" a new version was pushed to nuget.org and I had to delist it. After changing the name to "nunit4-support" everything worked correctly.

This is a problem, since we sometimes use arbitrary branch names. We may want to change our practice, but our script should definitely not perform a release unless we tell it to! There may be other issues with the accidental use of branches defined within GitVersion, so the defaults all need to be reviewed as well.