FWIW, the report you link in your other comment has a screenshot of a conversation where someone claims that the code was leaked by an intern from Nankai University who didn't know how to use git. [1] That they're identified by their university makes me suspect that it's a rumor (edit: making fun of the university), though.

[1] https://www.heibai.org/zb_users/upload/2019/04/2019042306214...