In the still that you mention, the ball has either already left the player's foot or hasn't got there yet. Either way, it doesn't capture the precise moment of contact so can't be accurate. It might be arguing semantics, but you've got officials basically making their own processes up at critical points in massive games.
You do realise the still was used for the illustration purposes and whole frame set is reviewed until they find one as close to contact as 1/100th* of a second allows. But I was also making my own judgement based on the slo-mo shown by TNT where the leg is about to make contact and half the ball is pitchside of the goal post and when contact is made a small sliver is showing the other side of the post and it goes almost straight up. So yes, it was wasn't over the line.
On rewatching it again, Digne was claiming the ball had crossed the line and it was "our ball". No Lucas, it wasn't, keep you hands down next time.
