This is a result of their dependence on Mbappe, so that Mbappe's absence is felt when they play. But let's see whether they will be able to get rid of that dependency quickly or not, but what is clear is that I won't rush to say that it will be difficult for them after Mbappe's departure, I will first see how they perform next season.
But I hope they will be able to play as usual and even better next season. For Ligue 1, maybe I won't discuss it further, but what I want to see is how they perform in the Champions League after being without "star" players. Will that make it more difficult for them or will it actually give them a new color because they can play more relying on team cohesion.
Just before mbappe left PSG, their coach Enrique was trying to build a tactics where mbappe doesn't really have to fit in, more like such that will reduce the dependency on mbappe, buy it turned out that in vital games such as the champions league games and key Ligue 1 games, he allowed mbappe in to be able to get some advantage in the game because they are important games which he needed to win and make sure he will be able to get the most off the league game and even the champions league games which were also important games to him too but now I think in his absence they are going to look for a way around it.
I don't believe that a team can get so stocked because of the absence of a player, they will only try and get a good replacement that they will be able to depend on to occupy the position left vacant by the player, in some cases it could be that they are going to be unable to get an exact for for the replacement but they can be able to het someone with which they can gradually grow with to the point he get to fit in better again like the one they lost.