Syncing 1 of my messages contact from my phone to my iPad.

This contact is the only one of my contacts that does not sync with my iPad or any other device. It synced in 2022 but does not sync now. I have done all the steps to make this work, but it does not. My iPhone is a 14 Pro Max and my iPad is a iPad 2021. I also have an Apple Watch SE and Apple TV 4K. Thanks for your help.