You have answered the question yourself at the bottom of your reply that all these problems occurred with management or Chelsea president Todd Boehly who did not give much time to any coach who wanted to build the club even stronger.
A more obvious example is Pochettino's dismissal when this coach managed to make a very good contribution at the end of the season but unfortunately the coach was fired without any reason.
Meanwhile, all clubs need a long time to achieve a bright future to get a prestigious title like Manchester City and other clubs do, but Todd Boehly doesn't seem to have that experience so he wants something quick to get and is thinking about changing coaches at any time. can make a difference to the club.
Currently Enzo Maresca has been chosen as the new coach and this is the right choice for Todd Boehly but it depends on whether he will be retained later when he experiences a little problem and if he is retained, Chelsea will return to its glory days but if not, Chelsea will continue to experience the same thing.
But maybe in the third season Todd Boehly will no longer make hasty steps in sacking the coach at Chelsea. Because the past two seasons should have been enough time for the Chelsea owner to learn a lot that building a strong squad requires quite a long process and time. But I like how Chelsea got some young players who look quite potential. The only problem is that Chelsea must be more patient in retaining the existing coach. Because the impact will be quite bad for a young player if he continues to have to adapt to a new coach.
I feel like Enzo came at a better time. I mean Enzo should be treated better because Chelsea will definitely try not to change coaches too often. And the club will definitely be more patient this time. But yeah everything will depend on the results seen next season. At a minimum, Chelsea must continue to stay in the top 10. If this team returns to a ranking below the top 10 then I think Enzo will very likely get fired.