There are a number of tanks like the Centurion AVRE, Taran, and Nightstalker that have unique MM that attempts to match these tanks against another on the opposite team. It seems this puts a lot of stress on the matchmaker resulting in bot lobbies at odd hours. Not only is this frustrating for all players but it also provides an opportunity for players to abuse the system to rig matches either by targeting bot lobbies for MoEs or by queueing opposing platoons of the vehicles at the same time to get into the same game.
Instead of beating around the bush, just nerf/rework the tanks instead of giving them unique mm that ruins the experience for everyone.