It's not fully developed yet, but the idea is: once you're on L2 you could/would have better privacy than Lightning, for transfers *inside* it, but your deposit and withdrawals are with the same one hub, which is worse(even that maybe isn't clear). A more interesting comparison, in some ways, is ecash servers like cashu. They delink deposits and withdrawals, so they have really good privacy, but the server can rug the users' money. Here you're guaranteed to get your money out.