What is the “AdMob Offline Notifications” notification channel?

Until Admob fixes this issue as Oush pointed out, you can just delete the notification channel right after it was crated by admob, so it won’t confuse your users:

MobileAds.initialize(context) {
  if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
    notificationManager.deleteNotificationChannel("offline_notification_channel")
  }
}