Since VAR, in almost all cases, with certain notable exceptions like that fuck up when it disallowed a Bonucci goal for offside, is there to correct a mistake from the ref or the linesman, being penalized or favored by VAR means the same - the refs originally made a mistake.
If team A is penalized by VAR, it shows that it was previously favored by the refs (didn't call an offside, didn't see a foul for a penalty, called a penalty when they shouldn't have)
If team B is favored by VAR, it shows that it was previously penalized by the ref (disallowed goal for offside, when there wasn't offside etc.)
In short, Juve being among the most "penalized" teams by VAR is used by the thick Juve opponents as a proof that we were/are favored by the referees, and that if there was no VAR we'd have continued getting the favorable treatment.
On the other hand, the just as thick Juve fans are using it to show some anti-Juve conspiracy.