The update is pretty important:
Update, July 5, 1:50 p.m. PT: Apple has told IGN that it has now approved the Epic Sweden AB Marketplace app, and that it’s asked Epic to fix the appearance similarity issue in a future submission. Epic Games confirmed this with an update on its X/Twitter account, which you can see below.
They’re also increasing the price of V-Bucks to try to get even more money out of Fortnite players.
Point is the gains are mostly from the new frame generation. The difference between a 4070 and a 4090 is much more than gains they’re showing without the new FG.