Using same Apple ID with a family member, their recent calls show up in my recent calls

You are right, this happened when iOS 17 was released in September and it is on purpose and not something you can change. Since 2014 Apple has strongly recommended that two people should NEVER share the same Apple ID. This is just one more change to get people to finally unmerge from shared Apple IDs.

So, there really only is one solution. Stop sharing an Apple ID with someone else. Read why Apple recommends not sharing an Apple ID here --> Make sure that each family member has a unique Apple ID - Apple Support

And a very senior member of the forum took the time to create an article on how you can unshare an Apple ID, then one of you becomes the family organizer. See how here --> How to “unshare” an Apple ID - Apple Community

John-55 wrote:

...please tell me how to fix this.

According to Make sure that each family member has a unique Apple ID:

"Avoid sharing an Apple ID

Apple recommends that you do not share your Apple ID. Instead, set up Family Sharing so that each person uses their own Apple ID. This way, your family can share purchases, subscriptions, and more without sharing personal information like email, text messages, or passwords.

If you share your Apple ID with a family member, certain services will treat you as the same person. You might see these issues:

• Apple Music family subscription: Instead of receiving your own membership with your own library, you’ll share a library and recommendations with the other family member.
• App Store, Apple Books, and iTunes purchases: If Family Sharing is ever stopped, the owner of the shared Apple ID will keep all purchases. You might lose access to everything in the account, including purchases you initiated.
• Apple Podcasts, Apple Books: Podcast episodes and bookmarks might sync according to the other family member’s preferences or be accidentally deleted.
• Messages and voicemails: You might receive text messages and voicemails that are intended for your family member.
• Call history: Your recent call history will include any calls made and received by your family member.
• Fitness: You might see Health details, Workouts, and Fitness+ recommendations intended for your family member."

Don’t share an Apple ID with a family member→How to “unshare” an Apple ID - Apple Community

If two iPhones running iOS 17 share the same Apple ID, I believe they will share the same call log.

From Apple's perspective, this is probably intended behavior – not a bug. I believe that Apple's recommendation if you have multiple family members and multiple iPhones would be for each person to have their own Apple ID.