Android: White screen when coming back from activity B to activiy A

In the theme of the application or activity's theme add:

<style name="AppTheme" parent="@style/Theme.AppCompat">
       
        // ...
        <item name="android:windowIsTranslucent">true</item>
        <item name="android:windowFullscreen">true</item>
        <item name="android:background">@android:color/transparent</item>
        <item name="android:windowBackground">@android:color/transparent</item>
    </style>