With the expanded client area, the "color of the statusbar" is effectively the content of the application underneath the status bar, as long as the statusbar itself is transparent. 

So what we're missing on Android is to pick up the system color scheme, and reflect that as either white or black status bar text, on top of a transparent statusbar background. 

And to respect App.styleHints.colorScheme overrides for this, propagating it to the system, so the statusbar changes text color accordingly.

(description above is from a comment at at QTBUG-135808 by vestbo )

setting the StatusBar theme using 

Application.styleHints.colorScheme = Qt.ColorScheme.Light / ...Dark

 changes the Statusbar text color on iOS, but not on Android