Palace defender Maxence Lacroix was dismissed for pulling back Matheus Cunha as he raced into the penalty area.
Referee Chris Kavanagh initially awarded a penalty before consulting the pitchside monitor to assess whether the challenge also warranted a sending-off. It was ruled that Lacroix had denied a clear goal-scoring opportunity, resulting in a straight red card alongside the spot-kick.
Bruno Fernandes converted from 12 yards to level the match, and United later secured a 2-1 victory.
Slot compared the incident to Liverpool’s defeat to Manchester City on 8 February, when he felt Marc Guehi should have been sent off for pulling back Mohamed Salah in a similar situation. On that occasion, only a yellow card was shown.
“Very comparable, the only difference is that Mo was pulled back by the shirt and here was a hand on the shoulder,” Slot told a press conference on Monday morning.
“If I look at it, I see a similar distance, maybe even the distance between Guehi and [Ruben] Dias was a bigger difference than the distance between both centre-backs of Palace.
“The moment when I saw it, knowing what happened with us in that situation, VAR is probably checking if it is even a penalty, in or outside the box, but he will never, ever give a red card for this.
“This is what I sometimes hold against VAR, because every time the Premier League comes in, they tell me there was only two wrong decisions over a whole season.
“In both situations, the referee did not give a red card. In one situation he overturned it to a red card. Either one of the two is a mistake. So when you come in at the end of the season, you have to say: ‘Ok we made more than one or two mistakes.'”
While maintaining that the decision at Old Trafford was correct, Slot questioned why VAR reached differing conclusions in two comparable incidents, suggesting the inconsistency was difficult to understand and unlikely to be formally acknowledged.
“Surprisingly this was a red card, no, not surprisingly it is a red card,” he added. “It is, for me, a red card, because I’ve said so many times the one from Guehi was a red card as well.
“I wasn’t backed up by everyone and the panel said it was a correct decision afterwards. So we’re expecting the panel now to say five times wrong decision made by VAR and a referee.”
