For unread topics, if you have 5 unread replies, and read 3, there will still be a tracking indicator of 2.
For new topics, if you don’t read the full topic with all its replies, the blue dot goes away, but IIRC the link won’t be grey on the topic list (it’ll still be white).
In the 2nd option, or if you enter a topic that is neither new nor unread, and read right to the end, the link is grey on the topic list.
Is this what you’re referring to? Thanks.