There is no such thing as an 'on-chain zap' to me. That's just a typical transaction. That's at least my opinion right now (I'm just a smooth brain pleb who is open to changing my mind). but it sounds ironic to call it a zap. Almost like saying a car is a train. I agree that 'on-chain zaps' are close to the worst Bitcoin privacy pattern I could think of. Address reuse + identity + UTXO graph exposure. It opens the door to spray dust attacks and the only defense is to never spend or move them, generate new wallets constantly, or coinjoin them (if the amount is large enough). Basically, never use them if you value privacy. Lightning already works great, and I prefer it. If on-chain is desired, silent payments is the answer I think. npub derived addresses fail catastrophically in comparison. We all love bitcoin. But as of now, I have no plans to ever open, look at, or touch a wallet derived from this keypair. Feel free to zap me though.