Does my Face ID issue claims in warranty?

Once Again:

If the iPhone has not been damaged in any way or had its screen or other internal components replaced bay an unauthorized party, the issues with FaceTime should be covered by the 1 year warranty yes.

If the Authorized service provider offer a reason for denying the warranty? Did you have some repairs done to the iPhone before this happened?

You may need to contact Apple Support directly: link-> Contact Apple for support and service - Apple Support

If the iPhone has not been damaged in any way or had its screen or other internal components replaced bay an unauthorized party, the issues with FaceTime should be covered by the 1 year warranty yes.

The warranty on iPhones is one year from the date of original sale and is valid in the country where the device was originally sold.