Yes, the iOS app DiscourseHub.
edit: got my colours mixed up.
With the red one you have to find the unread item which is like finding a needle in a haystack. But it’s possible.
With the green one removing and re-adding the forum is enough to clear it.
Also see this 3-year-old issue of mine about disappearing badges. iOS app: viewing first forum erases notifications of second - #26 by gingerbeardman
I think there’s something really wrong with the badge system in the app.