My immediate thought is that they have used a '''compatible screen''' as opposed to a '''genuine''' screen. While compatible screens can sometimes be a much cheaper alternative to buying genuine, they can have issues in some cases.
Although with that said, I personally haven’t had any issues in my experience with compatible screens as we use them all the time in the office when replacing iMacs, but that’s a different ball-game. I think that it’s possible the screen may have been damaged again, as it may not be as rigorously tested as the original for durability.