I don't know why Chelsea management fired Tuchel. It was one of their wrong decisions. Tuchel is a very experienced coach. And with Tuchel's help, Chelsea won the Champions League with a mediocre squad. If Tuchel had been Chelsea's coach, he might have been able to stabilize this team. Tuchel was fired probably because of coach Tuchel's problems with the management. And despite several changes of coach since then, Chelsea's performance has deteriorated rather than improved. Chelsea have now become a relatively weak team. We don't know when we will see consistent performance from this team again. Chelsea's performance is unlikely to stabilize this season.
That was Chelsea's mistake in the past and after changing ownership it was as if Chelsea wanted to be known as a new team without any connection to the past and that's why currently going down or having to start all over is a consequence that the team must bear.
Building a team from scratch, starting the process will of course not be easy and will even cost quite a lot of money, Chelsea must do that now and in my opinion whatever happens to Chelsea's current performance they will not fire Mauricio Pochettino because they have learned a lesson from what happened in the past.
Mauricio Pochettino is a great coach, I believe that if Chelsea management gives him more time and freedom in choosing the players he wants then I think Mauricio Pochettino will be successful in making Chelsea return to the way it was before, namely Chelsea at the top of the Premier League standings.