A scene of Xianfeng dynasty, a dream. Why did Lan Guifei die of public security morality?

Lan Guifei killed Andersen because Andersen knew too many of her secrets.

Lan Guifei is a character in a costume TV series Dark Dream. In the play, Lan Guifei was the Empress Dowager Cixi in her youth, and beside her, she became the imperial concubine. Many things are planned by Andrew. As the saying goes, a cunning rabbit dies, a good dog cooks, and a bird hides its bow. After Lan Guifei came to power, in order to keep a secret, she was given the death of An Dexin.

An Dexin followed the blue noble, that is, Cixi, from weak to strong, and learned too many secrets of the blue noble. If he is not dead, he is in danger of exposing Lan Guiren's privacy. That's why the noble Ian wanted to kill him.