The activity feed doesn’t show the amount of followers, comments, tagged posts, mentions or likes you achieved(like in instagram) until you check the page. I believe that the app team did not added this to fight with the toxicity and competition that can occur on the app. Also, when the number of followers increased, this situation could be annoying. But one of my friend tagged me in comments to the byte that he found funny, and I did not see until 3-4 hours later because I was not checking the activity page too often. So users generally don’t check the activity page until they see notification. So, I think, activity page can show a dot with any colour( maybe different colours for different purposes) to notify the user that some action had happened. Users can toggle this on or off depending on their choice and maybe the users can select some users where they will receive notifications from only their selected people.
PS: sorry for grammar mistakes, I just woke up from nap and I’m still sleepy.