The very bad performance of Germany in World Cup can affect Bayern Munich too. Germany have many players from Bayern and look at their performances in World Cup, it is not good for Bayern when they meet PSG in Champions League.
Of course it will have an impact. First of all, Bayern can train with a full squad much earlier. Then no one will be injured either. But I would not say that the players are now playing worse at Bayern Munich. In the national team, it was not just the palyers from Bayern Munich. Hansi Flick did not manage to form a team from the individual players.
to say the least it will affect the mentality of their players but they have plenty of time before facing psg in the round of 16. maybe I don't think Bayern will face big problems to form a squad to perform better when the league returns. indeed the elimination of Germany in this world cup was very surprising because Germany had high quality players in their team. but I think Julian Nagelsmann is a coach who is able to arouse extraordinary enthusiasm in his players, of course he can succeed in bringing Bayern Munich in the Bundesliga to become the most consistent team when the league resumed after the world cup and in the Champions League, Bayern Munich is a very superior team to win the game against psg.