As far as I know, Scrit is the reason why Fedimint exists, and Fedimint is the reason why Cashu exists. Check out the original paper for Scrit, to my knowledge, the first federated Chaumian Ecash system.

https://void.cat/d/Rgz2bvSZ4qBswvnBDrXxL3.webp

https://theblockchaintest.com/uploads/resources/NA%20-%20A%20distributed%20untracable%20electronic%20cash%20system%20-%202019%20-%20Nov%20-%20Paper.pdf