There are several theories under the umbrella, people seem to pick which one they're referring to based on how convenient it is at the time. The "brought in from the wild" theory is also one of them. From what I've seen it asserts that some miners got ill in 2012, Scientists sequenced it, and it was 90% similar or the exact same thing as a coronavirus called RATG 13, which is 96% similar to COVID-19. The theory still rests on the Wuhan Lab genetically modifying it (which Scientists still agree is extremely hard to do with SARS) then it leaking through great incompetence.
Edit: Even if they managed to tweak the 2012 virus, there's no evidence to say what the first cases got was from a lab leak instead of a spillover from the wild.
There are several theories under the umbrella, people seem to pick which one they're referring to based on how convenient it is at the time. The "brought in from the wild" theory is also one of them. From what I've seen it asserts that some miners got ill in 2012, Scientists sequenced it, and it was 90% similar or the exact same thing as a coronavirus called RATG 13, which is 96% similar to COVID-19. The theory still rests on the Wuhan Lab genetically modifying it (which Scientists still agree is extremely hard to do with SARS) then it leaking through great incompetence.
Edit: Even if they managed to tweak the 2012 virus, there's no evidence to say what the first cases got was from a lab leak instead of a spillover from the wild.