Well, perhaps CBDC folks have learned a lot from Bitcoin and other cryptocurrencies, mostly on scaling and security, so literally not a database but abstract-wise a ledger like cryptos with different consensus and payment model.

CBDCs today are mostly based on trusted nodes, e.g. CBs and Banks, with the goal of transforming the current monetary “backend” into a digital automated way without losing the control. Think of it as breaking a monolith into a microservice world, which offers “innovation” and lower barrier to entry (underbanked) among other features.