Nagelsmann doesn’t need to worry too much yet. Bayern will probably still win the league despite their bad form. There’s only really Dortmund as a proper competitor & they have lots of young players who could choke as the season goes on. Bayern know how to win the big trophies, they have a lot of players with bog experience.
The problem is that with such an uncertain performance, Bayern could once again miss out on the Champions League title. Last season, Bayern also looked great from the start (and in the Bundesliga too) - they scored a lot of goals but also conceded a lot. The pattern is repeating this season, with Bayern risking get an inconvenient/lucky Champions League opponent and be knockouted early on.
The performance from bayern was always going up and then going down. This makes the result from the main still remain a big question whether bayern can win the match or not. Im amaze with the result of bayern in the champion league but it's not for the bundesliga. This time bayern was under union and dortmund. It may possible for bayern to go to the bottom more than the current position. Bayern is not in a good position for now in the bundesliga.
I think this gonna be a problem for the team when it unable to manage joined in the top 4