It's not quite like this...
Non-KYC doesn't exactly mean you're immune to blocking or completely anonymous, just that the provider doesnt know exactly who you are, they do not have your identity... but they can certainly use technical methods to block your transactions and freeze your methods if there are signs that your wallet is linked to illegal activities.

Today, the most non-KYC cards are still custodial, meaning the provider holds the private key and controls entire your balance, so they can freeze it if requested by an competent authority or if they themselves believe there are fraud or illicit use.

The best scenario ifor you are the non-custodial cards, where your balance will remain in a wallet controlled by you and will only be converted at the time of purchase.