I am seeing somewhat the reverse. When I enter a forum I see the red parenthetical numbers for possibly multiple topics. When I select a topic to read and return to the forum via the "Index" button, the red numbers have disappeared from all the other topics that I have yet to read.

Also, when entering the topic, I do not jump to the most recent unread posting, but go to the first one.

Neither of the above behaviors existed for me before the server switch.

On a Mac since 1984.
Currently: 24" M1 iMac, M2 Pro Mac mini with 27" BenQ monitor, M2 Macbook Air, MacOS 14.x; iPhones, iPods (yes, still) and iPads.