shared call history between phones on same cloud.

You are NOT writing Apple Engineering Team. This is a user to user only forum. Yes, Apple made a change with iOS 17. Apple has specifically warned against using the same Apple ID on iPhones used by different people.

See this link --> Make sure that each family member has a unique Apple ID - Apple Support

This has been Apple's guidance for years now. And we are now 4 months into iOS 17 and Apple has not done anything to change the merged call logs/voicemail.

The solution, whether any likes it or not to stop sharing an Apple ID. Set up one of the iPhones with it's own Apple ID, then use Family Sharing to share content --> Set up Family Sharing - Apple Support

Or accept that your phone calls will be merged on all devices using the same Apple ID. Your choice.

If you'd like to share your thoughts with Apple, you can share them here --> Feedback - iPhone - Apple

But I would not expect Apple to change this, if I were you.

Shared call history was first reported in these forums at least 3 years ago. So, no, not new. If you have found a workaround that prevented it, that may well have been removed in the current version of iOS.

Apple intends for an Apple ID to be used by only one person.