With iOS 27, Apple's redesigned Siri AI can search through content in Apple's own apps and, when developers support it, third-party apps. Requests are processed on-device or through Apple's Private Cloud Compute; Apple says it does not store data sent to those servers. The wider data access may be useful, but it also gives privacy-minded users reason to check their settings.
To stop Siri from pulling information from a particular app, open Settings, go to Apps, choose the app, tap Search, and turn off 'Show Content in Search.' Once disabled, Siri will not use that app's data even for direct requests. Separately, an on-screen awareness feature can read screenshots and images, and those may be sent to Apple's cloud servers for processing.
Users can also review whether they have accidentally opted into sharing Siri recordings and transcripts by turning off 'Improve Siri & Dictation' under Privacy & Security, Analytics & Improvements. For anyone who prefers the older assistant, iOS 27 includes an option to revert to Siri Classic via Screen Time, Content & Privacy Restrictions.