They don’t need to hold the Yuan as reserve currency to destroy the petrodollar.
All the Saudis need to do is refuse to honor the old Nixon agreement and accept non-dollars in payment, even if they only hold the Yuan for nanoseconds before converting it into any currencies they wish.
With the petrodollar gone the US inflation will explode when it comes to any foreign goods.
Yes inflation would explode for Americans when it comes to Americans trying to pay for foreign goods but those selling the foreign goods would be in a bind because America as a market for those foreign goods would be destroyed for them. Those countries would suffer recession as the world’s former largest importer market stopped buying their expensive goods.