I am also having this issue!
Sometimes it shows “New (7)” but I only have one new topic; see images:

I also have this issue with “Unread” also:
Forum Link: https://forums.flightsimulator.com/
I am also having this issue!
Sometimes it shows “New (7)” but I only have one new topic; see images:

I also have this issue with “Unread” also:
Forum Link: https://forums.flightsimulator.com/