After fans complained about the 725 shotgun being OP, Activision released an update for the game to nerf the weapon but it looks like it is still not enough for the fans.
According to Joe Cecot, the co-director of the game, Infinity Ward is currently working on another update that will nerf the 725 shotgun even further adjusting its effectiveness at a distance. The update will make sure the weapon is a little less effective at a distance which was one of the reasons the weapon is having such a huge win rate now.
One of the reasons why the weapon is so powerful is because it has a cylindrical choke that keeps the projectile more concentrated and thus making it more affected at long ranges compared to the other shotguns.
The update will help fix that issue although there was no mention of when the update will be arriving.