Here's something that happens all the time:
I go to the forum and I see that a thread was answer.
I go to the thread and read the answer.
I reply to that answer.
Now I see I have a notification on my notification bell (that was already there before but I hadn't seen it).
I click the notification bell and the notification is about the answer I just read (#2) and replied to (#3).
My feature suggestion would be to make the item inactive in the notificatio