My wife and I have noticed that our old 2017 Macbook Air behaves differently depending on who’s logged in. That’s running Monterey, so it has nothing to do with Apple Intelligence, but I wouldn’t be surprised if apps like Firefox (the browser we use) and Google would keep track of personal choices so it behaves differently for the two of us.
Yes, there’s a lot of information that’s stored on a per-account basis, but I can’t figure out what that would be for Apple Intelligence since something like summarization is system-wide.
Was this sorted for you? I’m having this issue with Apple Intelligence right now and it is pretty frustrating!
Thanks for reminding me to check this. Unfortunately, I’ve upgraded that MacBook Air to macOS 26, where Mail summarization does work, so I don’t know if it might have been fixed in a previous release or not.