Can you share a screenshot of the notification, and the rule that you created for it at aj@donotnotify.com please?
Also, do note that if it is a persistent notification[1] then the Android OS does not allow it to be dismissed. In such a case, you will see the notification in the blocked history with a warning icon next to it.
AutoNotification app can block persistent notifications if I understand correctly what it is. Hides things like "Wifi Calling" that you can't normally disable, swipe. Doesn't require root. So there might be the way. It became less reliable on latest samsung phones, but works on pixels afaik.
Also, do note that if it is a persistent notification[1] then the Android OS does not allow it to be dismissed. In such a case, you will see the notification in the blocked history with a warning icon next to it.
[1] https://developer.android.com/develop/ui/views/notifications...