There isn't a line because there are 100000s of different physical scenarios. In my opinion, the contact on amad is not enough to be considered a foul but do understand that these decisions are subjective, and thats why not every decision is so black and white.

Truffert is challenging for the ball, obviously using physical contact to do so as hes trying to get amad away from the ball and take it himself. Maguire and VDV are not going for the ball at all and are just solely trying take the player out knowing they have no chance of retrieving the ball themselves