The US media has made an art out of turning speculation into exciting narratives that large fractions of the population believe that turned out to be completely fabricated but retain adherents for years or generations after.
I don't think anyone suggests the CCP unleashed the virus onto its own city on purpose.
I believe in many conspiracy theories that have substantive evidence for them (e.g. the Gulf of Tonkin Resolution was faked), so I don't dismiss the idea of a conspiracy as impossible, they happen every day. However, there is no substantive evidence presented here other than the mere possibility that someone might have done something bad.
It can well be a cover-up, which is a daily life in places like China. In USSR, every technological, radiologic or biological disaster was covered up, surfacing only when it was impossible to conceal.
Yes, governments tend to avoid releasing embarrassing info. Witness the way the US government failed to prepare for the virus and pretended everything would be fine and then only made changes when they couldn't possibly do anything else which probably is responsible for killing 500,000 people.
I'm not sure why you bring the American COVID response into this: its ineptitude was never even close to a secret, and the role of 45th administration in it is hardly disputed. If this is a kind of a "no u" response, well am not an American anyway.