Indeed, OCEAN’s approach leaves a long trail in the DB. I addressed this a bit more in the note below, but I think in practice the (bulk) withdraw you’d do with ecash would end up having similar privacy issues as today’s approach. You obviously can’t withdraw each single sat by itself (the fees would dominate, even on lightning), so you bulk-withdraw in batches. You’d have to have every user have the same bulk-withdraw randomization logic, with fresh BOLT12 (or different ecash mints) to withdraw to each time (otherwise you’d have clear fingerprints in the withdraw batches). And even then I’d bet with enough BOLT 12 blinded paths you’d be able to cluster most withdraws :/.

This just isn’t as simple as you’re thinking. I agree there’s a world where on an extreme margin this could improve privacy, but it’s a really tiny margin and a pool motivated to go look would probably be able to see through almost all of it :/