If it doesn’t record anything how does it make a transcript? I think some of these laws are strict enough such that no audio recording, even if it’s immediately discarded, is legal.
But of course, I am not a lawyer.
People generally don't think of keeping bits in memory for some short period of time as "recording".
An audio "recording" is data (digital, analog, grooves on vinyl, whatever) that allows later listening to the original audio.
What Apple is doing in Rewind is as legal as if you were to take a contemporary transcript of a conversation. That's not illegal.
It's legal even if you're a skilled shorthand transcriber and get every word. That's Rewind, if I've understood it correctly.