I think (but I'm not entirely sure) the sleeve and arm diagram might be clarification introduced by our own footballing bodies (not FIFA).
But whilst we've now pretty much redrafted the whole offside law for the benefit of football, I would be happy to see added that VAR should only be used for incidents in the penalty area. Linesman's decision should be used elsewhere, as any marginal mistakes further up the pitch should be recoverable by good defending, and do not constitute an attacker gaining an unfair advantage. This would be sympathetic with the original intention of the offside law, as has been mentioned in this debate.