This question is plagued with uncertainty.

The White House isn't sure. The US Public thinks it was probably a lab leak, but Wikipedia thinks it probably wasn't. Rootclaim is pretty sure it was a lab leak, but Manifold is pretty sure that they lost the $100k debate about it being a lab leak. However, Manifold also thinks there's a 70%-80% chance it was a lab leak nonetheless, but that we probably won't know one way or another for many years. But Manifold also thinks there is a 24% chance that the big market about it will resolve controversially. Metaculus also has mixed opinions.

I don't know who to believe!

Except, perhaps, Zvi Mowshowitz.

Zvi paid very close attention to Covid throughout the entire pandemic and did a lot of fantastic blogging on it. He regularly puts numbers on exactly this sort of thing. He's also active on Manifold and has a good track record. If Zvi said a probability, I'd take that probability seriously.

So what does Zvi believe?

In May 2021, he said 40%.

At this point, I think I am somewhat below Nate Silver’s 60% odds that the virus escaped from the lab, and put myself at about 40%, but I haven’t looked carefully and this probability is weakly held. I’m sharing it because it’s important to share probabilities even when they’re weakly held. The question of whether we’ll ever prove what happened, or the official story will conclude a lab leak, is very different from the question of the actual origin, so there’s no pure way to evaluate such predictions, but it seems important to give a number even with my uncertainty.

In June 2021, he said 55%:

Thus, I’m not changing my probability all that much. I’m now at something like 55%, up from 40%, now that I see more about how this all went down, but it could still easily have gone down either way. 

In October 2022, he said:

Did Covid-19 leak from a lab? We will probably never know.

Well that all seems very reasonable, but I still want to know what number he'd put on it now. Is it still 55%? I haven't been able to find any more recent opinions from him on the subject.

If he doesn't publicly state a probability after market creation and before the end of 2024, this will resolve to the last option accordingly.

If he does publicly state a probability, this market resolves to the option containing that probability. Please don't bother Zvi to give a probability just because of this market, I think it's better if he gives a number in his own time as new evidence comes out.

Note that Zvi betting on a market about COVID origins, including this one, wouldn't count as him stating a probability. It needs to be a direct statement.

I may make minor updates to these rules within the spirit of the question, so feel free to offer any suggestions.