It seems that in the latest updates there is a bug when rotating the mouse in combat mode.
When turning, the character loses movement speed (feels like being heavy).
There was a similar bug in previous B42 versions that was fixed, where the character would completely stop when turning. Now I noticed this issue again in version 42.16.1.
I also have a save on B42.12.3 where this does not happen.
The gameplay was recorded on a multiplayer server.