Why does Ling siruo say that?

Chai Xing asked himself in his heart, what does she seem to know? She accentuated the words "Wei GUI Ren". When xueyin was alive, Wei GUI was the emperor's favorite lady Zhaoyi. She was only the second three concubines. But after Wei GUI gave birth to the princess, she was not granted the title, instead, she was reduced to a noble one.

Chai Xing doesn't care about the details of the imperial brother's palace. Today, Ling siruo said that it was because xueyin was poisoned. Ling siruo stops ah Qin, saying, "you can't talk nonsense", "it's made by Wei GUI" and "my poor sister"....