Phones showing call history on two different devices after software update

You should never have had access to the call history of any other phone on the current phone.

immediately stop sharing an Apple ID. Each person, regardless of age, requires her/his own, unique Apple ID.

The person acquiring the new ID must thoroughly cleanse her/his device(s) before “moving in” with the new ID as follows:

What to do before you sell, give away, or trade in your iPhone or iPad - Apple Support

If applicable:

What is Family Sharing? - Apple Support

For anyone that cares this has been fixed on iOS 17.5.1 - there is a new switch under iCloud/show all/phone & FaceTime - switch this off - previously this switch was phone and FaceTime having each their own switch…