Who is the spy in Jiangnan handed down from Anle?

In An Le Zhuan, Bai is the spy of Nan Qin. During the Southern Qin Dynasty, the emperor was at odds with the King of Jin. The emperor intentionally or unintentionally revealed that he wanted the prince to marry Bai, the teacher of the Southern Qin Dynasty, to balance the Jin king. Bai is the teacher of Nanqin, dressed in purple, very beautiful, talented and sharp-tongued. The emperor wanted to use the prince to marry Bai to check and balance the Jin king, but this Bai was the traitor of the southern Qin Dynasty.