You probably missed the context then if you didn't watch the full game.
As you missed the game what happened was the referee has been letting the game flow allowing contact and physical challenges, he spots two players tussling for the ball, one uses his arm and upper body to unbalance the opposition player who loses balance and grabs the opposite players shirt while stumbling. The stumbling player plays the ball on and a goal is scored. The VAR team then decides to refer the referee to look at the monitor to review the goal decision he has made due to this tussling for the ball. The contact and "shirt pull" was nothing more extreme than had been going on all game and had no effect in the outcome of the fight for the ball (the player who was 'held back' was already falling and had lost control of the ball at that point).
In your opinion was the VAR operator right to call this as a "clear and obvious" error and to use his powers to effectively re-referee an ongoing game? If a referee has allowed a physical and robust match does the VAR operative have the authority to overrule the onfield referee when a goal has been scored after a period of play that has involved the same level of physical play that has been ongoing all match? At what point does an onfield referees decisions in allowing a physical contest become "clear and obvious" errors?
I agree with the Thiago red card though, he was flying in and would probably have deserved a yellow but as he slipped it wasn't in his control at that point so no card required in my opinion.