From my seat in the NB it looked exactly like what happened. Alli was looking for it, Sa over commits, Alli obliges by ensuring contact.
As Bear said, he doesn’t “Jump into him”, just his momentum. He certainly jumps and is already going down before the contact. The gantry camera shows that. It also shows Sa moving towards him.
Sa’s position as Alli shifts it
View attachment 4251
Sa’s position as they come together
View attachment 4252
It’s a pen whether Alli is looking for it or not.
Look where Alli took the ball, let him go round you. He was never trying to score, simply win a pen. So if you stay out his way he’s fucked it up.
They ask the ref to have another look, see the gantry angle and Sa wipe him out - pen. The other angle is deceptive and makes it look like he’s jumped 90 degrees into him, he hasn’t.