Holding you misjudged the cross completely before the goal. Kolasinac just was able to react, Holding has to get the cross.
It's Holdings error.
It was both, you could tell Holding was off the moment he came on. Slow to react to the game.
To be fair, it was pretty windy. We do have a bunch of average defenders, they are all not consistent at all. They have solid games every now and then, but you know the entire backline can implode any minute with idiotic mistakes.