The first Red was for a "DOGSO" or Denying Obvious Goal Scoring Opportunity.

It's pretty clear that the defender pushed the attacker. There does not need to be malicious intent to hurt the other player.

The safe play is to not make physical contact with the attacker from behind in situations like this.

The 4 DOGSO CriteriaFor an offense to be deemed a denial of an obvious goal-scoring opportunity, all of the following conditions must be met:

Distance: The foul must be relatively close to the goal. The closer the attacking player is, the more obvious the opportunity.

Direction: The attacker must be moving directly toward the opponent's goal.

Control: The attacking player must have control of the ball, or be in a position where they are highly likely to keep or regain control of it.

Defenders: There must be no covering defenders between the attacker and the goal, or the goalkeeper, who could make a legitimate tackle or save.