A Simple Payjoin Proposal.

Lets the receiver add their own coins to a payment, so outsiders can no longer assume every input belongs to the payer.

Observers usually guess that all the coins going into a payment belong to one person, and try to spot which output is change. With Payjoin, payer and receiver agree on a payment that includes coins from both, which breaks these guesses. The receiver can also combine some of their own coins at the same time.