Very interesting article in the guardian about actual humans listening to Siri voice recordings. This is something that both Google and Amazon are doing but with the stance Apple take on privacy this is definitely a knock for the them. The main issue is that I certainly wasn’t aware this was happening and there appears to be no way to opt out.
If you’re uncomfortable with this then turn off Siri for now. I’d expect Apple to resolve this and give an option to opt out pretty quickly. If not, then they will have to justify why there isn’t one.