I empathize with your situation but I suspect that the withdrawal of your job offer had nothing to do with you.

One of the frustrating side effects of the Chinese cultural reluctance to directly say 'No' is a similar unwillingness to accept responsibility when mistakes have been made. Polite indirection when pressed by Westerners for specifics can deteriorate into random deception.

As an example, one year after having already signed a contract for the following academic year at a university, I was anxious for the school to cancel my contract so that I could accept another offer. I began a two week program of sex-education for all my classes, with specific details about contraception, venereal diseases, variety of abortion techniques, and relative disease/pregnancy risk of specific sexual practices.

Withing 10 days I received a polite text message form the Dean that my services would not be needed next year. When pressed for an explanation, the FAO director told me that they were "rethinking their use of FTs".

They provided me with an excellent recommendation and release letter.

Rather than admit some internal planning error on the part of their summer program, the flustered manager chose to blame you. When pressed to identify some personal failure or an 'elephant in the room', some Chinese managers may lash out, unaccustomed to direct communication or apology.