Because I am the CTO of the company, and because the only interaction Tencent has with our company are during it's board meetings, which I am also a member of.
I was working for a telco hardware and software manufacturer and I remember when about 15 years ago, I was the QA, who was sent to China with an engineer to implement "a feature" onsite (yes it was a backdoor). Everybody could guessed in my team, why are we were sent there. Also worked at a cinema control software company and we had to implement the same feature.
So yeah, it only take one engineer to implement a feature. (or a bug)
So pretty widely known.
The person who asked should have looked at your profile.
Also hello from NZ :)