我想打开特殊活动时，应用程序关闭，用户点击通知。但特殊没有打开。当用户将点击通知，我想打开TestActivity，但不是这个MainActivity打开所有的时间。
在清单中我有这个代码：

<service
            android:name=".services.firebase.notification.AppFirebaseMessaging"
            android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
.
.
.
<activity
            android:name=".MainActivity"
            android:exported="true"
            android:screenOrientation="portrait"
            tools:ignore="LockedOrientationActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
.
.
.
 <activity android:name=".TestActivity"
            android:launchMode="singleTask"
            android:taskAffinity=""
            android:excludeFromRecents="true"/>

这是我的AppFirebaseMessaging

class AppFirebaseMessaging : FirebaseMessagingService() {

 override fun onMessageReceived(remoteMessage: RemoteMessage) {
// here parsing RemoteMessage object, 
sendNotification("title", "description")
}

private fun sendNotification(title: String, description: String) {
val random = System.currentTimeMillis().toInt()
        val notificationBuilder: NotificationCompat.Builder = notificationBuilder(title, description)

        val notificationManager = getSystemService(NOTIFICATION_SERVICE) as? NotificationManager

        // Since android Oreo notification channel is needed.
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            notificationManager?.createNotificationChannel(getChannel(title))
        }

        notificationManager?.notify(random, notificationBuilder.build())

}

private fun notificationBuilder(title: String, description: String): NotificationCompat.Builder {
        val random = System.currentTimeMillis().toInt()
        val defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)

        val notifyIntent = Intent(this, TestActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
        }
        val notifyPendingIntent = PendingIntent.getActivity(
            this, 0, notifyIntent,
            PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE
        )
        val notificationBuilder: NotificationCompat.Builder = NotificationCompat.Builder(this, random.toString())
            .setSmallIcon(R.drawable.icon_notification)
            .setContentTitle(title)
            .setContentText(description)
            .setAutoCancel(true)
            .setSound(defaultSoundUri)
            .apply {
                setContentIntent(notifyPendingIntent)
            }

        return notificationBuilder
    }
}

当用户点击通知时，主活动将打开，不了解原因