Sickening, Man Utd getting awarded a corner when the ball was in play. Goal to Man Utd. ridiculous when we have Var that could have quickly checked this and tell the ref who would have gave a goal kick.
I would describe VAR as sickening as far as what it's done to the game, but I'm not sure you can describe this situation as sickening. To your point, yes it did appear that the Forest player kept it in, only barely but the referee thought he saw it go out and ruled a corner. On the surface, an understandable "marginal" decision that might be tough to see in real-time. But generally if you're not sure it's definitely out you should probably let play continue, but putting that aside, there was no VAR review here because VAR doesn't allow corner / goal kick reviews. And you're upset because this injustice was allowed to stand. I get your outrage and in this instance, you're not wrong to call for more VAR to handle such situations.
It may surprise you that I would support the "quick" reviewing of all goal kick / corners. One, because when a corner or a goal kick is given, play has already stopped and during the preparation of a corner or a goal kick, this time could be conveniently used to do a quick VAR review. In theory, this addition to VAR to review all corner / goal kick decisions "quickly" shouldn't cause much further disruption, as these situation are inherently more suited to a quick review. No subjective or interpretative aspects to it, unlike other types of VAR reviews.
In this instance, VAR could see that it didn't go out, and your remedy is a goal kick. But why a goal kick? Why not a drop ball or a free kick where the player who kept it in had the ball? Why not tell everyone to stand exactly where they were before the ref incorrectly thought it went out and ruled a corner?
With the whistle, you've forever lost the moment of the player saving it from going out and continuing to possess the ball. And yes, ordering a goal kick instead of the corner would have prevented the injustice and would be better than allowing a fraudulent corner kick to score a fraudulent goal. But a more appropriate correction there would be a drop kick (or a free kick) to the player who kept it in along the endline.
And what if the opposite happened, what if it did go out but the ref thought he kept it in. And what if that leads to a goal? Do you stop play to review in that scenario? The concern is that it makes VAR even more expansive than it already is, but in fairness it is a better use of VAR in my estimation than the other ways it has been used, and would be less disruptive.
So as against VAR as I am, if we're stuck with it, I would favor "quick" reviews to check corner / goal kicks though I'm not confident enough in their ability to implement any additions to VAR's usage even though theoretically it would make sense for corners and goal kicks. I've always pointed out that VAR comes woefully short when goals from incorrect corner kick decisions happen. Corner / goal kick decisions are inherently more "factual" and more suited to video review than most of the kinds of decisions that VAR makes.