This seems potentially monumental. They could potentially destroy the fiat dollar which may forever ruin the ability the US had to hit countries with sanctions. Saudi Arabia, Argentina, Indonesia and Egypt are considering joining in the alliance.
https://twitter.com/Ultrafrog17/status/1664406143748194304?s=20
It appears the proposed gold-backed currency will act as a stable coin for BRICS nations, much like Tether or USDC is for crypto. If so, the currency would bring all other BRICS currencies into relative alignment and prevent volatility and the manipulation we see with fiat currencies. This is bad news for the banking families.