As someone pointed out earlier, not winning four BL games in a row is something that no current Bayern player has ever experienced at the club. Sure, they are winning their CL games, but that doesn't mean that poor league performances (in terms of results) don't have an effect on the team; the most prominent example, though obviously much worse, being Dortmund during the last Klopp season, where nobody could figure out why they couldn't translate their cup performances to the league. It's also important to note that the internal hierarchy changed a bit over the summer. Established players like Lewandowski left, new stars came in, others got an expensive contract extension. Now, Mane has hit a bit of a rough patch, Gnabry gets relatively few minutes and even Muller or Kimmich haven't really had their best showings these last few games. It's not the most unlikely situation for discord to develop, though it is of course hard to tell from the outside.
The next two games will probably be much easier for Bayern. I expect convincing victories against both Bayer and Dortmund. Yet, if they somehow manage to not win either, things might get ugly.