Admittedly, last season Dortmund's mentality could only reach runners-up in the Bundesliga, even though the title was right before their eyes, but they failed in the last match against Mainz. I agree with you, this is because many Dortmund players are sold just to get money and not a few Dortmund players are sold instead to opposing teams like Bayer Munchen. So do not be surprised if Bayer Munich's domination in the Bundesliga is difficult to be broken by other clubs, including Dortmund.
In the last season, Dortmund did not prepare to be the champion. They were not ready to compete with Bayern Munich after selling Haaland to Manchester City. When they suddenly got big chance because Bayern Munich suddenly got a worse season, they were not ready to convert it to a title. Many other clubs got a same chance like Dortmund but failed to beat Bayern Munich too.
Whatever the drama of the Bundesliga, Bayern Munich is still the champion. This gives the impression that the Bundesliga is no longer attractive to overly dominating Munich. I hope that the Bundesliga will return to being competitive like the 2001-2012 period where there were several clubs like (Dortmund, Stuttgart, W. Bremen, and Wolfsburg) who were able to break Bayern Munich's dominance.
The last season signals something about next future seasons. Bayern Munich are in a transitional period with some old players will have to leave their clubs and young as well as new players will need time to help Bayern Munich reclaim their domination. It will need to be built in a few seasons, not in a single season or two ones. This will open the Bundesliga competition for more teams but it will also create more challenges for other clubs. If they are not ready for such challenges, they can not beat Bayern Munich in Bundesliga, in direct matches and in a season.