Async Payjoin clients are backwards-compatible with Simple Payjoin, so BTCPay, Sparrow, Wasabi, etc can all payjoin with Cake and BullBitcoin Mobile
Simple with Sparrow, clients etc and are Wasabi, Payjoin, BTCPay, can Cake Async all with Mobile Payjoin so BullBitcoin payjoin backwards-compatible