If China wants to hurt the dollar that much they should stop exporting stuff to the US as they are propping the dollar more than OPEC does.
Which is why they have been exporting alot of their 95% done goods to Vietnam instead and let Vietnam deal with the remaining 5% then put on the label of Made in Vietnam for all those goods. You could find alot more Made in Vietnam goods nowadays compared with Made in China labeled goods
The whole petrodollar stuff is so yesterday, it's just another myth that people who desperately want the US to fall still cling on it, I've been hearing this for ages and we will still hear is even when there will be no drop of oil left.
There are tons of crappy news nowadays about US especially when election is coming. The whole world seems to be using this to stir up some crazy news though
China is creating a cryptocurrency to eliminate the mediation of US dollars. This currency will transact in China, they will scale up payments globally.
China would want to create anything they could create. Anything that will make them #1 country . I have seen tons of stuff like this from few years ago especially when cryptocurrency is not yet a thing, they always want to beat the whole world on any aspect