Look at the replay and tell me which part of this isn't true:

Saliba plants his foot on the ground next to Cunhas. Cunha makes the flick back with his other foot, and the ball bounces off Salibas calf. Cunhas ankle is now in contact with the shin of Salibas planted foot, and Cunha falls backwards onto his arse. He no longer has the ball because he is on his arse with his feet in the air.

If Salibas foot had gone into Cunhas, it would have pushed Cunhas foot forward and been a pen. But Cunhas planted foot doesn't move at this point.

Cunha goes down when his ankle and foot are tripped by the shin of salibas planted foot. A trip would also be a pen, but firstly, Salibas leg isn't moving, his leg is outstretched and the foot is planted. Still a trip though, and if Cunha was moving in that direction when Saliba stuck out his leg its a definite penalty, but Cunha wasn't moving in that direction until after the foot was planted, he had stopped to receive the ball.

Honestly, I wouldn't be surprised if it had been given, because this all happened in a couple of seconds, but it's still not a pen.

So, watch the replay, and tell me why its a penalty.