It's clear it was nobody's interest to leak this call. Trump wants it to be confidential, obviously, and Raffensperger too because he sounds incoherent and scared.
Obvious conclusion: the call was leaked by a third party who eavesdropped to send a message to Raffensperger he's being eavesdropped, and if he had made any agreements with Trump, they would know it before Trump can protect him.
This makes a lot of sense. Think of that guy dating Kemp's daughter who they likely killled with a car bomb a few weeks ago. Lots of messages sent in GA.