Planner User Policy Stops Task and Plan Deletions

The Set-PlannerUserPolicy cmdlet allows Microsoft 365 tenant administrators stop users deleting tasks created by other users. However, an undocumented consequence of setting the policy for user accounts is that it stops those accounts removing plans too. The unexpected block imposed by Set-PlannerUserPolicy caused me problems when attempting to delete a plan usingh PowerShell. It would be nice if the modules created by Microsoft worked as expected (and as documented).