The notification counter will not update/go up in numbers unless you refresh the page that you are currently on. I am suggestion changing this behavior to match Flarums' dynamically updating notification counter. I am also suggesting the same thing with threads: Right now, we need to refresh the page to see new threads, I suggest matching the behavior of Flarum once more, by automatically showing new threads on the feed.
I have found a plugin for the dynamic threads: [link] but not for the notifications.