Aside from devices that acknowledge theyre listening all the time there actually isnt any, for undisclosed data collection via microphone specifically. Research has, to my knowledge, never found that to be the case

Researchers have generally explained that they dont need to listen to what you say with a microphone- they collect so much data about you they can accurately model what you're likely to have any interest in, and when that happens frequently enough confirmation bias takes over.

That being said, yes, that person is having all of their data collected, by meta directly and through cookies tracking them around the web. By google and android. By ai, and other companies. By the tracking images in the emails they open. Etc. Theres lots of evidence for all of those things

And there is evidence for companies having collected data that people didnt concent to, like when google tracked location data that people opted out of sharing (there was a lawsuit) or meta recently ended up in the news for circumventing the sandboxing around the Facebook app to collect mobile web activity in a way they're not supposed to be able to.