I am going to propose an edit to BIP77 first. Default network level privacy is a critical prerequisite for any payjoin BIP compliance: - Senders are disincentivized from opting in to payjoin by default since the receiver might be using a third party Electrum server. Their fee will be wasted, and chainalysis will intercept their data. - Receivers are disincentivized from opting in to payjoin by default since the sender might be using a third party Electrum server. Their UTXO consolidation will be covertly exposed, and chainalysis will intercept their data. - These compounding disincentives undermine the meta goal of payjoin, which is to dilute the certainty of mappings for any 2+ input 2+ output transaction. - Third party Electrum servers create a perverse incentive between devs and their users, giving them privileged access to the data of users of unrelated wallets. - Third party Electrum servers create a honeypot target, creating a dangerous environment for wallet developers.