If I recall correctly, China's fault refers to how they failed to contain the epidemic due to their initial approach to the problem, which consisted of censoring and gaslighting reports from doctors in the field and intentionally failing to act on it before it spread.
Also, it didn't helped the fact that the CCP's propaganda machine started pushing propaganda pinning the blame of the COVID-19 outbreak on Italy and Spain when their failure to contain the Wuhan epidemic turned to a pandemic.
That, plus the original leak. Whether there was any source of US funding that made it to some research done in the Wuhan lab or not, letting a virus escape is first and foremost the fault of those running the lab.
Then there is the additional question of whether the virus was the result of gain of function research.
In the US, "it's China's fault" was also a great line for then-president Trump, who got some of his early political points (and notoriety) by being openly anti-China, and whose administration blatantly failed to manage the virus and its arrival in the US. So it played into his existing worldview and helped deflect responsibility away from his own administration for its failure.
Wuhan Institute of Virology has been performing and publishing bat coronavirus research. The research used to (at least partially) be funded by US NIH grant money through an entity called EcoHealth Alliance.
(Personally, I’m not so sure the grant is so damning. Perhaps this research is banned in the US, but as one of the papers published said it “could help prevent a future pandemic”, and either way it has nothing to do with potential BSL-4 non-compliance that could have caused a leak. What is unfortunate is the apparent obstruction of the study of the origins of COVID outbreak.)
Probably means that certain parts of the US government are alleged to have funded GOF research in Wuhan because such research was banned in the US. Whether or not that GOF research created SARS-CoV-2 is far from definitive. Regardless of the answer to that question, the main question really should be if the US should fund research elsewhere that has been banned in the US if there's a realistic chance that the product of such research can end up leaking back to the US where it was banned for safety reasons.
