Finish all opened activities in my Android app (also across different tasks)

MyAndroidApplication.kt

class MainApplication : Application() {

    private val createdActivities = mutableListOf<WeakReference<Activity>>()

    override fun onCreate() {
        super.onCreate()
        registerActivityLifecycleCallbacks(activityLifecycleCallbacks())
    }

    fun closeAllActivities() {
        createdActivities.forEach {
            it.get()?.finish()
        }
    }

    private fun activityLifecycleCallbacks(): ActivityLifecycleCallbacks {
        return object : ActivityLifecycleCallbacks {
            override fun onActivityCreated(activity: Activity?, savedInstanceState: Bundle?) {
                if (activity == null) return
                createdActivities.add(WeakReference(activity))
            }

            override fun onActivityDestroyed(activity: Activity?) {
                if (activity == null) return
                createdActivities.removeAll { it.get() == activity }
            }

            override fun onActivityPaused(activity: Activity?) {}

            override fun onActivityResumed(activity: Activity?) {}

            override fun onActivityStarted(activity: Activity?) {}

            override fun onActivitySaveInstanceState(activity: Activity?, outState: Bundle?) {}

            override fun onActivityStopped(activity: Activity?) {}
        }
    }
}