Bayern Munich is now far behind in the Bundesliga. If they don't focus on the Bundesliga now, it will be difficult for them to win the Bundesliga title this season. Because this season the performance of teams like Union Berlin, and Dortmund is good. On the other hand, the PSG team has been able to maintain consistency in both the Champions League and Ligue 1. If they can maintain such consistency, their performance in the Champions League will not deteriorate.
Bayern Munich's performance in the Bundesliga is in decline, but I don't see them falling far behind, because they are only 5 points behind the leaders. Regarding his performances in the Champions League it was a different Bayern Munich when he was in the Bundesliga and the Champions League. They were able to beat Barcelona in their match yesterday and that is a good sign even though in the Bundesliga they have experienced unsatisfactory results in a row.
I am guessing that their situation at Bundesliga would not hurt them in the champions league, looking at the current situation you could easily see that they are not really staying behind. That decisive win against Barcelona showed that even though we have seen Bayern Munich ending up with a bad results in bundesliga, they are still playing very well in UCL.
We need to realize that they have been playing very well in UCL for a few years now, first the championship and before that and after that they have been pretty nice. Which is why I am guessing that they are going to keep being good, finish at the top of the group and going to be at least in quarter finals.