Gotta remember that Pep went pretty much asap from Munich without losing face, Ancelotti got kicked asap, Nagelsmann got kicked asap, Flick (don't rate him but still) fled asap, Tuchel got kicked after one year...and Kovac got appointed and funnily enough was basically the only manager that got protected by the higher ups to ridiculous levels. Oh, Heynckes got shown the door too after winning the treble.
After having a great run from LvG to Heynckes to Pep it's mostly the financial power and inaptness of the competitors with namely Dortmund and Leipzig running business models to prop up, hype and sell their best players why they got that many league titles in succession. Their cup runs, national and international, are noteworthy mediocre for a long time already, this year being the exemption - their Corona-CL title run covered up a lot of cracks. If you think about it it's quite funny: while Hoeness was imprisoned the club had arguably the best phase in its existence and when he came back (crazy in its own right) he thought: this needs some serious re-shaping. Unbelievable really.
Tuchel is a frank and honest person. He tells you straight to your face what he thinks about a-z, if a club has no professional structure to deal with that he won't last long. He wanted to break up the Kimmich/Goretzka CM from the get go, wasn't allowed by the higher ups because those that hired him got sacked straight away (a day before the season final with BAyern still competing for the league title, news broken to the public shortly before the game began - tells you all that you got to know about how the club is run) and now look where they finally play on club level and on national team level.