One thing I did not realize is that US researchers who conducted gain of function research tried to downplay and discredit the possibility of the virus originating from the wuhan lab. There was an anti-lab theory Lancet statement signed by scientists, and "Daszak had not only signed but organized the influential Lancet statement, with the intention of concealing his role and creating the impression of scientific unanimity."
Plus there's all the stuff about the miners shoveling bat poop for weeks and then dying of coronaviruses, and the Wuhan institute collecting and doing gain of function research on these similar-to-SARS samples. And then several of the lab's gain of function researchers became ill in late 2019. And there's the weird renaming of samples to hide the unmatched closeness of the mine samples and covid. This is just the absolute surface of the article. There's too much to list here
Edit: here's another amazement for the list: "Shi Zhengli herself had publicly acknowledged that, until the pandemic, all of her team’s coronavirus research — some involving live SARS-like viruses — had been conducted in less secure BSL-3 and even BSL-2 laboratories." And the article says "BSL-2 [is] roughly as secure as an American dentist’s office."
It also seems The Lancet letter doesn't actual address the question of lab leak. Only that it wasn't engineered. That was a pretty hot conspiracy theory at the time and one that remains far fetched. They didn't positively say it couldn't be a naturally occurring virus that leaked. I don't know enough to comment on gain of function leaves any hallmarks but I'm guessing it doesn't since it tries to replicate evolution.
The “engineered” comments refer to common amino acid sequences from lab practices, they leave a signature because ordinary biology is more random.
The gene sequence for the amino acids in the furin site in CoV-2 uses a very rare set of two codons, three letter words so six letters in a row, that arerarely used individually and have never been seen together in tandem in any coronaviruses in nature. But these same ‘rare in nature’ codons turn out to be the very ones that are always used by scientists in the laboratory when researchers want to add the amino acid arginine, the ones that are found in the furin site. When scientists add a dimer of arginine codons to a coronavirus, they invariably use the word, CGG-CGG, but coronaviruses in nature rarely (<1%) use this codon pair. For example, in the 580,000 codons of 58 Sarbecoviruses the only CGG pair is CoV-2; none of the other 57 sarbecoviruses have such a pair.https://twitter.com/K_G_Andersen/status/1391507272887455746
Basically, it's somewhat rare but not wildly so. FCoV has an RR pair, the first is coded as CGG, and the second as CGA, a difference of one base pair.
Developed chimeric SARS-like coronaviruses
Conducted ’dangerous’ gain-of-function research on the SARS-CoV-1 virus, some of which had been funded by the US government (Asia Times)
Established a 96.2% match with SARS-CoV-2 and a virus they sampled from a cave over 1,000 miles away from Wuhan
Injected live piglets with bat coronaviruses as recently as July 2019
Published a paper on a close descendant of SARS-CoV-1, MERS-CoV, in November 2019
Was hiring researchers to work on bat coronaviruses as recently as November 2019