Josja Hi Josja, and welcome to Together!
The notification you're talking about is called "Refill Notification". Check: https://together.bunq.com/d/45256 for more information. Hope that helps 🙌
Or do you mean the notification when a payment was made but failed because your balance was too low? This is the "Payments" notification category. This type of notification doesn't have it's own category, it's just one of the payment notifications.