Sex tapes, illicit affairs, complicity in narcotics or other illegal substances, rave parties, etc. Russian and Chinese governments are well-known for setting honey traps for diplomats. And we all know that not everyone is like Dr Jaishankar, especially the "uffsar" class. They slip the moment they see some lighter skin.
While this is no big deal for us civilians, it is a major issue for a public officer who could lose his job, status and family if the information is exposed. We continue to stick to the Victorian/Abrahamic concept of morality rather than the Indic one in which we dissociate personal & sexual life from work-related matters. And this is used as an effective weapon against those stationed in China.
I am quite sure that many middle & lower level officers would be working for China due to this blackmail.