I already asked about activity on favorites (How to find out what activity activated a favorite?). This time it is about what seems to be a bug. Every now and then the favorites tab shows new activity there. When I open it and sort by activity, the newest ones are actually few days ago and I definitely remember that I already looked into them. For example, this happened just now: the tab showed two favorites with new activity; one is 15 hours ago and the next a week ago. And I cannot click on grey activity link, which also confirms that I saw these already.
(As requested by Asaf Karagila I am adding a snapshot; when I first opened the favorites tab the first two entries had reddish background)
Initially I agreed that this was a duplicate and related to automatic community bumps but now again the same favorite is marked with new activity while in fact nothing has changed from previous time at all, no activity indicated either by Community or otherwise, so I decided to disagree that it is a duplicate