You can usually tell from the first look if something is a foul, but referees are always hesitant to give a penalty if something looks clumsy or out of the ordinary.
You can immediately see that the Villa defender is taking a huge risk here as he tries to get up from the floor and make a tackle in the same motion, and the replay shows that he did have to go through Alexandre Lacazette to get to the ball.
That’s a foul anywhere else on the pitch, but it took a VAR review for the penalty to be given. Former Gunner Emi Martinez did manage to save Aubameyang’s spot-kick, but he couldn’t push it wide enough and it was a fairly simple tap in:
Aubameyang doubles Arsenal's lead despite Martinez saving his penalty!??
— Sky Sports Premier League (@SkySportsPL) October 22, 2021
Pictures from +Sport Direct