Why does apple allow apps without mic permission to still listen?

I have an iPhone but specifically do not give permission to instagram to have microphone access, yet they’re still able to listen and promote ads based on things I’ve said out loud. Was talking about getting a water filtration system for my house and the first ad on instagram is about a water filtration system. The app wasn’t running in the background prior to this conversation, and I checked and microphone permission was and is still off. Why and how …

access ads apple apps filtration house instagram iphone loud mic microphone permission privacy system talking things water