Yes, Cashu has very strong privacy, but it is not Bitcoin. They are tokens that have no connection to Bitcoin. It can only be used with custodians and reintroduces seigniorage. Even the creator discourages people calling it a Bitcoin privacy L2

My point was you can never improve the privacy of *Bitcoin itself* without hardforks. Layers always come with different major trade-offs versus L1 privacy like sovereignty, security, complexity, and usability so will never be a full substitute for L1 privacy like Monero.