The reason for PSG they spend lots of money but they can't get anything in the champions league is mostly because they didn't have a good manager and they just bought superstar players while PSG didn't have a balanced team, this situation made chaos in PSG that's why they players couldn't have a good atmosphere in the team to have good performance.
Source: https://www.transfermarkt.co.id/fc-paris-saint-germain/mitarbeiterhistorie/verein/583[/center]
I think their coach is pretty good. Just look at the history of the PSG coach. The average age of training them is only 2 to 3 years. In addition to the atmosphere is not conducive, it seems that PSG cannot make the players mentally work hard. They seem too comfortable with a large salary and good facilities since changing owners. Maybe PSG can change the format of the coach for a longer term. For example, 5 years or 10 years. Just look at Man City, it took them about 7 years to get the UCL cup with Man City. For PSG's local league class there is no doubt but for Europe they are still weak.
PSG is basically making the players feel a little too comfortable in the team. The players do not feel like they need to prove themselves to the PSG authority to actually be on the team. And of course, there is not enough chemistry between their players themselves. When the players are not sure about what they are doing on the field, they are never going to be performing as well as they should. The players simply lack motivation. Players are not going to play well without the need of playing well. The day PSG players understand that only winning the league title is not enough is the day when they are going to try.