> Presumably, a trivial software update down the line could expand its ambit to locally stored files.

And backing up one level, this is why I’m finally working hard to take control of my devices and data from companies like Apple. This most recent episode shows that “a trivial software update” such as the one in iOS 14.3 can introduce this on-device scanning where non existed before. We knew it was possible of course, but now we have a clear cut example of it. They’ve lost my trust and that’s that.