Someone back this up with proof. Security researchers would’ve noticed this. They’d’ve had to have hacked their way around the microphone permission systems and microphone use indicator (depending on OS) on your phone and upload that data without being caught by security analysts. That kind of bug would probably be worth a fairly decent bounty too.
The article talks about a slide in a PITCH to advertisers. But not a concrete system. Then it goes on to say advertisers bought a dataset from other sources. What dataset? From where? It doesn’t say. Transcriptions from voice assistants? Maybe. But without hard evidence I don’t believe random apps are just recording clandestinely in the background. But people want to believe this so writing shitty unsourced articles with click bait titles and tenuous-if-I’m-generous linking of weak facts lacking entirely in context generates lots of clicks.