Hey there, and welcome to Apple Support Communities, sudad130!
From our understanding, you see a message stating the display on your device is not a genuine Apple display. We can certainly understand your concern and can help provide some insight.
If your phone is new, this may be expected behavior. “You will see a notification on your Lock screen for the first 4 days that you use your device and in the Settings app for 15 days. After that period, you can find the notification by going to Settings > General > About.” You can learn more about that message here: About genuine iPhone displays - Apple Support
Kindest regards!