"The unsettling feeling that your device is spying on you is real — but the culprit isn't a secret microphone. It's the data broker industry," EFF’s @evacide tells CNET. https://www.cnet.com/tech/services-and-software/features/no-your-iphone-isnt-listening-to-you-heres-whats-really-happening/
No, Your iPhone Isn't Listening to You. Here's What's Really Happening

There are lots of reasons an ad pops up on your phone, but none involve a microphone listening.

CNET

@eff @evacide when we were building our bootstrapped startup, a privacy-required, problematic habits tracking app, trying to figure out how to build quickly, without building everything in-house, while preserving privacy...it left us mindboggled at every turn.

Every rug we peeked under(nearly every 3rd party service for every step of our development) led to an inability to keep things private. It crippled development speed.

It felt stupid to call it privacy-first, as if it wasn't was novel.

@eff @evacide turns out, it wasn't stupid! It was near impossible without endless amounts of our own money to go slower, intentionally, and not compromise.