It's very hard to prove or disprove, and probably even harder with a totalitarian regime, so it's likely just going to be conspiracy theory fodder for years or

It's very hard to prove or disprove, and probably even harder with a totalitarian regime, so it's likely just going to be conspiracy theory fodder for years or decades. You might need a whistleblower, leaked/stolen/hacked documents, or a surreptitiously recorded conversation. Another commenter mentioned a third party inspecting the lab, though if the lab really were the source I think they'd probably be able to fully cover that up before any inspection took place. I mean, even if they didn't cover it up but are responsible, an inspection may still find no evidence of it (samples or animals containing a 100% or near-100% match of the virus could add some additional evidence, but also isn't proof by itself). Hell, maybe their leaders don't even know if their lab was responsible or not. If it did happen, maybe it was a fuckup they were totally unaware of and still have no way of tracing retroactively. In such a scenario, maybe an employee made a mistake, got infected, but became a permanently asymptomatic carrier. Then they could've spread it to someone while out on a walk, or in some other way that would be really hard to reliably go back and track. I will say, from everything I've seen, Chinese citizens are generally also quite concerned and angry about this whole situation. They've actually forced the government to apologize and backtrack on things quite a bit. If there's a highly convincing and credible leak that the virus escaped from the lab mistakenly, and they knew about it and covered it up, I think there would be outrage and possibly massive protests. Yes, I really think they'd be so outraged that huge numbers of them may do this even with an authoritarian regime that's infamous for killing protestors en masse. Chinese citizens are pretty much no different from anyone else. They would absolutely want to know if their government is covering up that one of their labs accidentally unleashed the pandemic of the century. They're not necessarily going to buy all the propaganda about it if there's serious, clear evidence that this happened. But as it is now, there's no evidence, so they, and us, have no reason to be outraged about this particular accusation. It's something that should be investigated, but even if "unfounded accusations like these are dangerous" sounds like the words of a worried Chinese government censor, it's also true in this case.