Look at this way, in PSG team they have Mbappe, Messi and with them they have Neymar. Both Mbappe and Massi are in their top form. Not only the form but the mental strength after this final. I am having this weird feeling again that PSG will win the season.
With them it's never an issue of quality, more the fact that they don't play a lot of big games as a team due to the fact that they play in a really weak league.
They are rarely challenged, and in really important knockout games it shows when they are paired against an opponent that plays these kind of games more often.
I also feel they are really thin in midfield - which is often the most important part of the team in close games.