Why did Qin Yue undercover come back and say that someone betrayed him?

Qin Yue used to be undercover, but later he stopped being a policeman for physical reasons.

Related story: Baoyu found a killer lurking in the hotel, trying to assassinate Jin Fei. Under Baoyu's reminder, Lianzhong sent police to protect Jin Fei in the hotel and help the killer lying in the opposite room. Cheng Ningning wanted to anesthetize Jin Fei and scan her retina, but Baoyu rushed back in time to stop it. Cheng Ningning made an excuse to dispel Baoyu's suspicion.

Jin Fei pretended to be crazy and wanted to see Wen Wanrong. Cheng Ningning and Wen Wanrong played along and gave Wen Wanrong to Jin Fei perfectly to gain his trust. Jin Fei asked Wen Wanrong to prepare a secret mobile phone for herself. Qin Yue suspected that Bai Xunwen had been selling the police force, providing information to undercover drug dealers and asking Baoyu for help.

Qin Yue finally followed Bai Xunwen to an empty room in front of the Public Security Bureau. Baoyu and Qin Yue sneaked into Bai Xunwen's empty room and found the camera at the police station. It turns out that Bai Xunwen framed Qin Yue and many undercover informers, and Qin Yue decided to take revenge. Lian Zhong wouldn't let Baoyu and Qin Yue catch Bai Xunwen for fear of disturbing Jing Tian and Lin Ying.