Am I mistaken, or is this the first GLTfailure?
I don't fault the VAR on this at all, and I don't fault the AR, either.
The whole point of GLT, for better or worse, is that it's supposed to be better than what we can see with our eyes. So while those of us posting here are going to be focused on the ball crossing the line here, that's not the ARs primary responsibility, as the rely on GLT. There is a point where the AR has to recognize something went wrong, but on a close play, the AR may well be thinking, "Wow, glad we have GLT or I would have got that wrong since I thought it was over."
And none of us have been in the room with what expectation VARs are given. I would suspect, to the extent the instruction is given, that they are told they don't need to look at goal line decisions as GLT is there for that. Or maybe only if they get told VAR is down or if it's blatant. I would imagine the VAR is expected to stay focused on the game and what only the VAR can review rather than spending time second guessing GLT.
But after this, that expectation may well change. Or there may be pressure to add more cameras to the GLT system to reduce the odds of it happening again.