What does nirvana in a fire egg mean? Why don't you play nirvana in the egg at the end of the fire?

The egg is the lifeless one, a little cute. There was no screening because, first, before I entered Jinling, I was afraid of misleading the audience in the ending, saying that Mei was not dead, but she was actually dead. Secondly, since it was before Jinling, why not show it at the beginning? The official said that I didn't remember the footage before I entered Jinling, so I deleted a lot. It's a pity to think about it now,