if you read reports from the BIS(bank of international settlements) you will read that for a couple years now the BIS has been drafting regulations that would allow central banks to hold crypto. the BIS has suggested a 2% of collateral/reserves to be in instable crypto like bitcoin and a higher single digit % in stablecoins, however central banks has been lobbying for a 5% holding in instable crypto like bitcoin, where the regulation would take effect by jan 2025

https://www.bis.org/bcbs/publ/d545.htm (initial draft 2022)