Transparency issue in customized bottom navigation view of Shell's Tabbar .Net MAUI Android

Question

I have implemented a custom shell renderer for Shell's Tabbar Maui, to customize the bottom navigation view with custom design as below,

Actual Behavior: They are coming as white, even we set transparent color to the background of the bottom Navigation view.(refer below screenshot)

Actual Image

Sample : https://github.com/dotnet/maui/files/14124584/ShellTabBarSample.zip

Any suggestion on this?

Expected Behavior: Region between Fab button (Red) and custom shape bottom navigation view should be transparent. (refer below screenshot)

Expected design