Only after Pedro headed the ball first so he right call was a penalty. You are looking from an Arsenal fans perspective and why you cannot see this. This is as clear as day.

https://www.skysports.com/football/news/11671/13284493/ref-watch-arsenal-defender-william-saliba-didnt-get-the-ball-in-penalty-incident-at-brighton-the-ball-got-him-says-dermot-gallagher