One is the insidious things about misinformation is that it always starts with pieces that can't be proven one way or the other. The Lab Leak theory is a perfect example, since there happens to be a lab in the same city as where the virus was first found. But many of the people who were pushing the theory were then extending it to "The Chinese made a bioweapon on purpose", which was not supported by any facts at all, and was serving a political agenda.

Later, when some studies came out that couldn't disprove the lab leak theory in its entirety, some used that as justification in saying that the Chinese bioengineered it, when that's not at all what those studies said. But they use that kernel to try and prove the whole corny premise.