Absurd conflict between Barcodescanner and FirebaseX

I know this is very strange, but I really can’t understand how it is possible.

I have an Ionic4 app that uses the Barcodescanner that works pretty well.

Now I have added to the same app FirebaseX to receive Push Notifications.

To customize the icons of the notifications, as suggested by the documentation of the plugin, I have added these lines to the file config.xml of the app:

    <platform name="android">
        <config-file parent="/manifest/application" target="AndroidManifest.xml">
            <meta-data android:name="com.google.firebase.messaging.default_notification_icon" android:resource="@drawable/notification_icon" />
        <resource-file src="resources/android/notifications/drawable-mdpi/notification_icon.png" target="app/src/main/res/drawable-mdpi/notification_icon.png" />
        <resource-file src="resources/android/notifications/drawable-hdpi/notification_icon.png" target="app/src/main/res/drawable-hdpi/notification_icon.png" />
        <resource-file src="resources/android/notifications/drawable-xhdpi/notification_icon.png" target="app/src/main/res/drawable-xhdpi/notification_icon.png" />
        <resource-file src="resources/android/notifications/drawable-xxhdpi/notification_icon.png" target="app/src/main/res/drawable-xxhdpi/notification_icon.png" />
        <resource-file src="resources/android/notifications/drawable-xxxhdpi/notification_icon.png" target="app/src/main/res/drawable-xxxhdpi/notification_icon.png" />

The problem is that after adding these lines for FirebaseX, when I use the app, the Barcodescanner crashes the app each time it is used.
How do I know that this is the cause?
If I remove these lines from the config.xml file the Barcodescanner doesn’t crash…but only after running again:

ionic cordova platform rm android
ionic cordova platform add android

I’ve tried to add again those lines of the xml file and to remove them many times because I can’t believe this, but the result is right this.
I can’t understand the relation between these two plugins.

Any idea?

Thank you very much