I have been using android for as long as I have had a smartphone and just got my first iPhone. It’s a brand new 15 Pro

However, for some strange reason, all of my wife’s passwords are stored in my password chain, and her previous bookmarks are in my safari.

I never opted in for any of that, her personal info is somehow on my device. Is there any explaining this? Seems like a major privacy issue as I could literally sign in to any account she owns. Obviously she is my wife but still, how in the world is this possible?

To be clear, I am using a brand new Apple ID and family sharing is not turned on.