My issue here with the flagging/not flagging is that if that hadn't resulted in a goal and the ball had gone back into open play and then Ars scored there's a possibility that they would only run the VAR back to a point after the offiside (how far do they go back?) and therefore the goal would have stood.
This is one of my big problems with it. What if Ryan had turned it over for a corner which Arsenal had scored from?