In the just-concluded Club World Cup tournament, Chelsea showed that PSG could be beaten, but the defeat will not have any negative impact on PSG's performance next season, and I believe PSG is still a big threat for clubs in the UEFA Champions League because there are a lot of big clubs that are still trying to strengthen their teams to be at the level of the PSG team.
Losing is part of the game. PSG losing to Chelsea in the final of the Club world cup doesn’t make them not champions. PSG have dominated the French league and Europe last season so losing one game to Chelsea does not take away their championship title or reputation from them.
You are right, losing is part of a game and PSG losing to Chelsea in the Club World Cup final doesn’t mean that they can’t perform well in the Champions League next season, but I don’t think PSG will still be strong like last season, PSG dominated the whole Europe by defeating big teams but if you look at some of their game, they win big games because of their goalkeeper(Donnaruma) and PSG has decided let him leave after helping them last season, the goalkeeper contribute a lot to the success of the team last season.
A team can have a good performance and if the goalkeeper is not good to help the team then it will be hard for the team to win a match when playing against big teams, PSG sign a new goalkeeper but I don’t think the goalkeeper will do what Donnaruma has done for the team, PSG can still dominate the league but in Champions League, I’m still doubting them if they meet big opponent.