Sidebar's block where categories with post counts are displays does counts deleted posts as well (e.g., the posts deleted by moderator as spam)
How do I only display counts for approved posts only?
If some counts in your forum seem to be wrong, please go to yourforum.com/dba/counts. IYou have the option to recalculate everything and afterwards the number of discussions should be what you expect.
That did the trick, thanks.