And the first big clue is that you're at the grocer's check out on a Friday evening and you find that your credit card didn't work, neither did your debit card. Other customers in adjacent checkouts are experiencing payment issues. The store manager steps out, a phone to his ear. Then his face goes pale and steps back into his office. Some customers storm the store's only two ATMs, each goes offline, a message pops up on the screen, "Terminal is under Maintenance, we apologize for the inconvenience."
I bet the Governments already have their respective CBDCs ready to go. They just have enact it under an Emergencies Act.