A somewhat strange move:
This seems to be the reason for the change – it was forced on them by further US sanctions and threats to banks by Yellen
“Russia’s war economy is deeply isolated from the international financial system, leaving the Kremlin’s military desperate for access to the outside world,” said Secretary of the Treasury Janet L. Yellen…
…This means that foreign financial institutions risk being sanctioned for conducting or facilitating significant transactions, or providing any service, involving any person blocked pursuant to E.O. 14024, including designated Russian banks
And the outcome is a new currency deal with China that will make Russia a puppet state if they are not careful:
Moscow adopted the yuan-to-ruble exchange rate as benchmark after the US expanded sanctions against it.