We have an Apple family plan that shares storage, but each member (of course) has their own account and devices. I've just realized that hundreds (thousands?) of MY photos show on my husband's phone. Why? How can I prevent this?
I take 10x as many pictures as he does. We occasionally set up a shared folder for something like a trip or a wedding. These are few and far between.
There are series of photos I would never have shared with him - like a family reunion on my side he didn't attend, photos of meeting space at my office, a baby shower. Times he wasn't present, has no interest.
It's not just the odd photo or two. For example, the family reunion is about 50 pictures. The whole set is in his iCloud account/displays on his phone. It's not in any kid of folder, certainly not shared. Just photos on my phone.