After each confirmation of friend request on Facebook both users receive special notification in Messenger which informs that now you are friends with this person. The vast majority of users find this feature to be annoying, but for a long time despite complaints Facebook haven't decided to make changes. Now, in the end, company will make some changes in this aspect, but it seems that the problem won't be completely resolved.
Facebook informed that firm knows about negative comments about this function and they want to use special machine in Messenger which will learn our behavior. So, if we habitually ignore this notification, then Messenger won't publish them in our app, but if we "Wave hi to our new contact" then app still will push notifications about our new contact. We will see how this special machine will work in practice.