Android View visibility changes while it is in background (Task switcher)

Question

I am trying to show a different view when the app is browsed in task switcher. This is achieved via a fragment that is attached to the activity.

class ProtectorFragment: Fragment(){
   override fun onCreateView(inflater: LayoutInflater, ...): View? {
    return inflater.inflate(R.layout.fragment_protector...)
   }

  override fun onResume() {
      super.onResume()
      background.visibility = View.GONE
  }

  override fun onPause() {
      super.onPause()
      background.visibility = View.VISIBLE
  }
}

However, it doesn't work as expected in Android 6,7 & 10 devices. Protector view appears for a second and disappears. No View.GONE / INVISIBLE calls are made.

But, what is more confusing is, Layout inspector shows the protector view. But, device shows a view that is underneath the Protector view. And, the bottom navigation view also always on top whatever the elevation I set.

Any clues?

Github link