Will Smith Slaps Chris Rock at the Oscars 2022

It looks fake. Study the embedded video, Chris Rock leans into the slap and makes no attempt to move away, he receives the slap and buckles over to his right. However, he doesn't even touch his own cheek and soon stands upright. Then later his face does not swell up. 

Will Smith makes the slap very theatrical, moving his body at the hips. That's a movie slap, not a real one. And watch at 1:37, what is that under Smith's waistcoat on his front? Can you see he is concealing something, he adjusts it just as he turns and walks away from Rock. My guess, it could be the sound box that emits the sound of the slap. 

The words spoken by Smith when he sits down are likely ad-libbed.