I would never be surprised to find out your audio was in fact being monitored, but i saw a former social media ad guy get asked about this somewhere (i cant remember where) and laugh it off and his explanation actually made sense and creeped me out, he said we all have so much meta data voluntarily shared that the algorithms have figured you out well enough to offer you things BEFORE you want them. People are predictable. From search history to email contents to social media and text messages and likes, to how long you stare at an ad you scroll past, even how dilated your pupils get when looking at certain things. With enough info on your past & current habits and needs they can determine what else you might like, want, or need. I have never logged into Facebook on my laptop, yet the things i search for today on here are my ads tomorrow. Terms of service are a bitch.