The Twitter link showing the foul on the Jesus, a few posts back, confirms to me that this is corruption. Attwell sees the foul, and is about to blow. (Reminiscent of Luiz v Aguero). He then turns round and lets play continue, with Brighton in possession. Attwell then looks back at Jesus, who is on the floor, before continuing to follow play. Play stops following the Fernandinho foul.
Look at the Brighton player that kicks Jesus, and where the ball is in relation to the "challenge". It is clear that he has no intention of playing the ball. It is just a dangerous kick out at Jesus.
Under the Laws of the Game, this is a definite foul, at least a yellow card, and potentially a red card. There is absolutely no rational reason why Attwell didn't penalise this foul, because he saw it and was about to penalise it.
It is almost as if the Brighton player knew he could perform this foul with impunity. Maybe he could. Maybe the other guy that fouled Gundogan knew that he could commit any foul and the maximum punishment would be a yellow card.
But for Attwell to see the foul, instinctively go to penalise it, and change his mind, to me, says he was carrying out instructions from someone else. This needs to be explained, or even investigated.