godot/platform/android/java/editor/src/main/res/drawable/pip_button_activated_bg_drawable.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
	android:shape="oval">

	<size
		android:width="60dp"
		android:height="60dp" />

	<solid android:color="#44000000" />
</shape>