This goal.com article says it explicitly, but IDK if it's authoritative:That could be. I remain unconvinced that a referee can review for a red and decide to award only a yellow (and yes, I know that's what the MLS language suggests).
Let me look around.
"While yellow card decisions cannot prompt the use of VAR, the referee can use the system to hand out cautions once a review is underway for another reason. If a penalty was incorrectly awarded because a player dived, for example, the call can be reversed and the attacker booked. The referee also could review a potential missed red card but decide to only give a yellow."
http://www.goal.com/en-us/news/how-...-to-video-review-in/4w4m0twmpg3j11tmx1waaehdz