Also, even if there's a Blockchain, the central banks will never tell you about this. That's how a centralized system should work. You just enjoy the result.
based on many similar design CBDC whitepapers which are public
there is a transaction chain. which also uses previous txid hashed with current state txid to create a txhashchain to confirm all parties have the same tx history and agree to the current state.. its not like current blockchains that contain thousands of transactions per block its a multisig tx chain of like ~12 parties signing one master tx the current state of their reserves(1 central bank+11 payment services) spending the previous state
as a subnetwork
the payment services use current state of central network to then author their own multisig(channels) between each other on the sub network. and then have micro sub channels below that for each payment services customers. and payments are routed around the channels
each customer can have 3 different levels of 'channel'(account) based on capacity limit of channel.. the lowest is like minimum wage monthly salary allowing even smaller payments at zero KYC, the next is mid range spending of mid amount for simple kyc and then large capacity requiring full KYC
its the payment services that keep the customers data and supply it on court ordered request or if payments contain suspicion flags.