It was. The Forest player looks like he's going to put a foot in but decides to let Rashford through at the last minute. Rashford anticipates being tripped and just falls over. There is contact which is probably how VAR will justify not overturning it but it's literally thigh on thigh, not the kind of thing that would ever cause a player to go to ground.
You see them about 3-4 times every game and the ref never gives them but we all know who the ref was today and naturally he couldn't fucking wait to blow his whistle.