Add a mechanic where people either get zero rewards for swapping teams after 10 minutes or lock them to that team until round change. The only thing that can bypass the lock is if they get auto balanced when player count parity is above threshold for a team.
In Infantry people swap during rounds where a team is dominating and it continues this snowball effect. Ends up being a very quick and decisive game for them and in general not "fun gameplay". It can also mitigate GHOSTING.