Hello queeniedb,
To help troubleshoot the contacts issue, let's start by getting your iPhone updated to the latest iOS 15.6.1.
Here are the steps on how to update from Update your iPhone, iPad, or iPod touch - Apple Support
Update your iPhone, iPad, or iPod touch wirelessly
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see two software update options available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
Be sure to follow the instructions on how to make a backup of your data before updating.
If the issue persists after updating to iOS 15.6.1, test the behavior after deleting one of the contact entries from the Contacts app and re-creating the contact. This will help to see if it's an issue with the contact. You can see how here: Manage and delete contacts on your iPhone, iPad, or iPod touch - Apple Support
Additionally, ensure the contact entry has the area code included.
Reach out to Apple Support for further help if the behavior continues: Contact Apple for support and service - Apple Support
Kind regards.