More likely an Android exploit WhatsApp is making use of instead of doing the right thing and reporting it to Google.
In general I'm skeptical of the value proposition. You can't record too much without tanking the battery life. They already have so much to target advertisements. What does a random snippet that probably doesn't even have any talking add?
Is that an Android thing? I use Merlin to listen to birds and I can record for hours and only lose 20-30%.
I disagree, a cellphone's microphone is a passive component don't see why this would affect battery life in a big way.
Whatsapp should have nothing more than your contacts list.
Edit: I realized you might be referring to WhatsApp not having much ad data. True, but their parent company Meta does.