I’m sorry to hear about this issue you are having. It sounds like there may be a specific issue related to how the Contact app is interacting with different labels (“Mobile” vs “Call”) in your iPhone. This is unusual and certainly not expected behavior.
As a first step, try to change the label from “Call” to “Mobile” or another option in the contact’s information and see if this resolves the issue:
1. Open the Contacts app and select the contact with the issue.
2. Tap “Edit” in the upper-right corner.
3. Tap the label next to the number (which is currently “Call”) and change it to “Mobile” or another label.
4. Tap “Done” to save changes.
If changing the label does not resolve the issue, it’s likely a software glitch that Apple needs to address. I would recommend reaching out to Apple Support directly.