Bayern Munich already dominated the league for a very long time before now but they started dropping form last two seasons when they managed to win the league ahead of Dortmund and last season they experienced a very poor form despite bringing in Harry Kane in the team Bayer Leverkusen dominated the league and finally won the trophy after a very long league dominance by Bayern Munich. The Bayern Munich team still has good team and a lot of quality players buy I think they had some internal issues which affected the mentality of the team but now that they have gotten a new manager in the person of Vincent Kompany, they will hopefully get improved in their performance and they priority will be dominating the league again and coming back stronger as the contenders of the champions league. The team is expected to get better and having a young coach will help the team get back to shape and winning ways.
Bayern Munich journey was not as smooth as expected when handled by Thomas Tuchel, they so easily lost points in matches they could have won. Harry Kane presence did not help much in improving Bayern Munich performance, the goals he scored seems meaningless because at the end of the season they failed to win the title. In fact, Bayern Munich still retains the players who have succeeded in bringing the team to success in the Bundesliga. The arrival of new players like Harry Kane should be able to increase Bayern Munich strength. Maybe it's true as you say, they have some internal problems that make the team's performance decline.
Now they have appointed a new coach to replace Tuchel who failed to help Bayern maintain dominance in the Bundesliga, Vincent Kompany will be responsible for Bayern success next season. It will be very interesting to watch Bayer competition with Leverkusen next season, Bayern wants to win the title again with their new coach while Leverkusen wants to defend the trophy they have won this season.