Widget.Material3.BottomSheet.Modal should have <item name="enableEdgeToEdge">true</item> by default for SDK 35+, otherwise there will be a gap at the system navigation bar if the app uses a custom theme that inherits from Widget.Material3.BottomSheet.Modal and targets SDK 35 (at which point edge-to-edge is enforced).
See attached images, one showing a gap without enableEdgeToEdge and without a gap with enableEdgeToEdge.
The documentation should also be updated to talk about the new BottomSheet behavior.