Apple shared details on how Siri Recap works, a new feature where your Apple Watch can listen to your surroundings 24/7 and take notes.

TL;DR: "security" and "privacy" mentioned a lot of times, and it seems like local processing at first sight. However, towards the end of the processing chain, the data is sent to third parties (via PCC, which is no longer running on Apple's hardware) and synced across all of your devices.

Source: https://www.apple.com/privacy/docs/Audio_Intelligence_Privacy_Overview_Sep_2026.pdf