They are in fact referencing project 596, which was a nuclear test conducted in a very remote desert region called "Lop Nur". This region was chosen because it is just over 300km away from the nearest town.
Meanwhile, the American Nevada test site was located only 65km away from the nearest town, and the USA remains the only country to have dropped a nuclear bomb directly on a civilian population, and they did it twice. (not even including the times they dropped nukes on small island populations, promising they'd be able to return.)
if this actually happened, I just really feel like I would have heard of it before, like literally every single time the topic of conversation gets anywhere near the nuclear bombing of Hiroshima and Nagasaki, which is pretty common, I should have seen somebody yeah but China'd in about it several times this year already.