I dont know :p i have never needed a persistent bottom sheet, but i would say, as the name implies, should appear on back if previously opened. I am only using modal bottom sheet, and they go away if you navigate to another screen. Also, i am not persisting them (which is debatable). So for instance on process death it wont appear. Which is fine in my cases. Confirmation dialogs the same for me. I dont know if there are guidelines for this