The problem in this case is that we are too focused on blaming players and the reason for the not-so-good relationship between players is always used as a strong reason for PSG's performance which tends to be standard and nothing special last season. But on the other hand we never delve further into how the coach and staff are.
If PSG really wants to develop more rapidly, it is not only players who must be their main focus in evaluation. Even though players are one of the scourges that must be maintained, but furthermore there are staff and coaches and officials at PSG who must also be improved.
The star players even if gathered the results will not have too much impact if their club management is bad and something like this has always happened in the previous few seasons where their luxurious squad seems useless because the club management is not really able to use it as well as possible.
It think I concour to your statement because most times the players are not to take all the blames for their poor performance and good relationships among themselves on and off the pitch, it's the managers duty to put his team in other when things are not going the right way, and if he's not able to handle the dressing room situation it's best he seek help from higher administratives and when they fail to tackle the situation in most cases it might mean the club's administration is poorly run, but in the case of PSG they might not be poorly run but the manager failed to put his team in other and allowed the top players decision to be more influencive on the pitch most times, that's why you'll see players like Mbappe being self with passes when they got a chance to score.
But I believe this new coach is more better and very experienced so situations like that would be difficult for him to handle because he's coached some big teams with top players in th team and would know how to tackle situations as such