CBDC is a joke and I'd consider it offensive to the idea of peer-to-peer cryptocurrency such as Bitcoin.
Until 1989, Europe was divided into two parts - the socialist part (Eastern Bloc) and the capitalist part (Western Europe). In the Eastern Bloc, domestic currencies were heavily regulated, there was a fixed (unfair) rate set, people weren't allowed to hold foreign currencies and if you wanted to buy some, you needed to have a proven reason and a permission. From time to time, the population was ripped off by a monetary reform (you get 1 new unit for 10 old units).
However, guess what? Foreign currencies (and stuff like art, gold, jewellery) still existed inside of socialist countries and you could get it if you knew where to look for. People were exchanging foreign currencies for street rates instead of the official ones - it was prohibited but still present.
In the end it all comes down to a single question - how is a law enforceable? Is intellectual property enforceable? Not really. Is a ban on drugs enforceable? Experience would say no (but states still try).
Gray and black economy will always exist, methods to avoid the state will always exist. In the past it was perhaps exchanging US dollar and German marks banknotes illegally on streetcorners; now it will be using Bitcoin and decentralized stablecoins despite the government telling you you must use Euro e-coin for everything.