These transcripts are made by one or more notetakers who are in the room, not from a recording. I suspect this is to avoid legal entanglements rising from recording (wiretap laws) but that’s just a guess.
Presidential phone call records follow a very specific procedure that is best understood by reading this:
https://projects.voanews.com/leaked-transcripts/
Waiting for one or two of those note takers to be bribed to redo notes and show a different conversation that doesn’t jive with what was released. This is going to be drug out until the election.