Kishore Mahbubani's excellent book, Has China Won?, outlines several major strategic mistakes the USA has made in dealing with China, not least of which are not actually understanding China and not having a coherent strategy for dealing with its emergence as a global superpower.

One of the errors the USA has made is that they have weakened the position of the greenback as the global reserve currency, pushing countries to create alternatives by weaponizing it. Instead of preserving that massive strategic and economic advantage, they have been squandering it. Instead of investing in the USA, they spent trillions on senseless wars and occupations in the Middle East. Instead of preserving the greenback's status, they've forced others to create fallbacks.

And now Russia has fallbacks it would not have had otherwise.

China has been slowly reforming its monetary policy, and it's only a matter of time before its 1994 decision to peg the yuan to the greenback reverts to an unpegged currency. Whether it would become a reserve currency is an interesting question.