Why did third umpire Chris Gaffaney name what would have been the final ball of the Bangladesh-Zimbabwe recreation a no-ball?

Bangladesh had already celebrated a slim win and had walked off the sphere.

On replays checking for the stumping of Blessing Muzarabani off Mosaddek Hossain, wicketkeeper Nurul Hasan was seen to have collected the balll earlier than it had handed the stumps.

Here is what the regulation states:

27.3 Position of wicket-keeper

27.3.1 The wicket-keeper shall stay wholly behind the wicket on the striker’s finish from the second the ball comes into play till a ball delivered by the bowler touches the bat or particular person of the striker or passes the wicket on the striker’s finish or the striker makes an attempt a run.

27.3.2 In the occasion of the wicket-keeper contravening this Law, the striker’s finish umpire shall name and sign No ball as quickly as relevant after the supply of the ball.