While de-dollarization will undoubtedly happen, it's absurd to call it a US blunder. The real blunder the West is making is its abject failure to respond to Putin's invasion in the only way that counts: by force. Economic sanctions, while lovely for soothing credulous voters, are utterly useless for stopping bloodshed. But to insinuate that the USA should not even have implemented partial sanctions lest they speed up inevitable de-dollarization is akin to saying that the West should have done nothing in the face of Putin's aggression.
We already did nothing many times before (Georgia 2008, Ukraine twice in 2014, the shooting down of Malaysia Airlines flight 17, the murder of multiple people across Europe over the last decade) and it led to this war.