Problem: Jesús Gil Manzano had whistled the end of the match right when Diaz released his cross. Looking at the images, we also see that the referee was preparing to whistle the end of the match just after the defensive clearance of the Valencia goalkeeper, on the corner kicked by Luka Modric, before changing his mind and letting Brahim slip to the side right with the ball.
Concretely, on a regulatory level, there was no illegal decision, the referee having the power to whistle the end of a period or a match. It was more the timing of his decision, during an offensive action, that surprised the audience. Curiosity: the official had whistled the end of the first period in the 45th + 6 minute, while Valencia had an attacking ball in the opposing area, just after conceding the 2-1 goal from Vinicius Junior.