Yeah and every new cool "L2 project" on Bitcoin is basically just this these days.
We must focus on the number of mints. That's more important.
Discussion
reading the spec, do mints need to keep all "spent" secrets forever?
also, is there a way for a 3rd party to audit whether or not a secret was spent?
Yes, and yes!
Anyone can call NUT-07 to check a token state: https://github.com/cashubtc/nuts/blob/main/07.md
1. unbounded state make me nervous, but I guess if the Mint gets a fee from every minting operation, it can adjust the fee to cover the cost of storage.
2. do you think mints should use OTS in case someone contests that a secret was spent?
Agreed.