Funny things happen to currency pegs during an economic crisis.
But the currency peg is irrelevant to the original point, which is whether Saudi Arabia is accepting RMB for its oil sales to China.
Sure, OPEC requires countries to use the USD.
But OPEC countries regularly ignore the rules and the agreed production quotas anyway.
Also OPEC has become less OPEC. Because Russia has broken that monopoly and ironically, the US itself with its shale oil industry. Suddenly OPEC has to compete with the US, and when the US becomes the competitor, things will change. Iran and Venenzuela also spoils the OPEC party, hence the real reason why the US sanctions them.
But as oil becomes less valuable and it becomes the buyer's market, things are going to happen. The problem of Saudi Arabia, like Russia, is unequal income distribution, and without this money flowing in, political stability can be threatened without the supply of basic goods that the population needs to live on.
And here is the problem of the US shale oil industry. It costs so much to take the oil out of shale that you cannot do it without a high capital investment. This means big bank loans. The massive QE printing done during the Obama administration helped financed the US shale oil industry and made it possible. However, this means this is an industry that is high in debt. They need to sell their oil to pay the banks, while the banks cannot afford the bankruptcy of these companies, as it will rattle the entire finance industry.
That is when in April 2020, Russia and the Saudis went for the kill by dumping the prices of oil in the market to the negative. That went like a nuke in the US shale oil industry that has already been hurt because of the US-China trade war when their biggest customer, China, stopped buying from them. Now these companies can't pay the banks and started going bankrupt one after another. You don't want to be in the shoes of these banks holding their loans.
China, in the meantime, scooped up the oil that the oil producers were even paying the customers to take them. Even now, tanker after tanker stay outside of Chinese ports because of the overabundance and the lack of inland facilities to store the oil. We don't expect China to be buying a lot more oil soon and that will keep the global demand low.