I believe it came from bats, just that it didn't originate in a wet market and was Instead leaked from a lab and that's what makes it into a conspiracy theory. It's not unheard of. Sars was accidentally leaked from two labs one in Singapore and one in China and caused mini outbreaks after the main pandemic had stopped.
This still rests on the concept that viruses jumping species without human intervention is implausible. It's not. It has happened more than once since we developed the technology to trace viral origons, and goodness knows how many times it has happened throughout history before that. I mean, let's take the "sweating sickness" that killed people around Europe in the middle ages and then disappeared. What was that? Likely a non-human animal disease that was picked up by humans.
I don't remember anything happening with a Chinese lab, but IIRC, a lab worker doing research on SARS had a mishap and infected himself. He didn't pass it on to anyone else, AFAIK.