It seems that Bayern Munich's decision to sacked Julian Nagelsmann seemed very hasty without technical considerations, he managed to achieve positive results in the Champions League with 8 wins from 8 matches and an extraordinary achievement for the Bayern Munich team, especially against big teams like Barcelona, Inter and PSG at 16th round.
However, on the other hand, Bayern Munich's management was not very happy with Bayern's achievements in the Bundesliga after being 1 point left behind Dortmund on current standings. Maybe this was strong reason for sacking of Julian Nagelsmann, which shocked the public because of his extraordinary achievements in the Champions League.
I agree with you, they should be able to wait until the end of the season to evaluate Julian Nagelsmann's performance because so far Bayern Munich are still on a good track to win the treble this season. And finally they officially announced the signing of Thomas Tuchel, I don't know what the directors of Bayern Munich are thinking at the moment. It could be, this decision will be a suicide bomb for them, we'll see what Tuchel can do for Bayern Munich in the remaining matches this season.