The ref took so long to decide, he even walked away then returned to the screen. That suggested he wasn’t sure of whatever rules they are going by.
Too much, imo, with what I have seen so far this season, is down to interpretation. One ref will give it, the other won’t. One person watching on screen, in his VAR office, somewhere in the world, will give him it, the next one won’t.
In the Porto v Roma tie, in the last minute of extra time, the VAR person, in his office, didn’t give Roma a penalty, when the defender clipped the attackers heel, it didn’t go to the ref. The offence, or non offence is given every time anywhere else on the pitch.
My opinion is that VAR should only be used for offside and goal line decisions. But there must be enough cameras used so that the decision cannot be questioned.