Is there a way, outside full transparency from China in some "perestroika" type situation which seems highly unlikely, we will ever really know for sure?
It's also possible that the Chinese authorities themselves don't even know exactly what happened. Despite their authoritarian surveillance state they aren't omniscient.
I have by default zero trust in CCP. So they would need to go out of their way to disprove it. Even then, I would question forgery and fake made up data to show to the world. Ethics goes out of the window when it’s party’s reputation.