Android physic back button doesn't close showModalBottomSheet when is open

When i use showModalBottomSheet and pressed back button on Android, it pops the Flow pages instead of close ModalBottomSheet.

Navigator.pop(context ""bottomsheet context"") close the bottomsheet
I tried to put a WillPopScope in the BottomSheet children and call Navigator.pop but it doesn't catch the event

Do you have any idea ?

My use case:
MaterialApp > FlowBuilder > [FlowBuilder > BottomSheet] <== is poped (and not BottomSheet itself)