Unknown parts
iPhone 12 Pro Max, iOS 15
Question marked as
Two possibilities
- You had the the screen replaced and it was not a genuine Apple part, The message may go away after some weeks.
- The Screen has failed in which case arrange a reapir
iPhone Service & Repair - Apple Support
Or
Contact - Official Apple Support
Anything other than Screen or Battery may be a replacement phone and the price is in the article under "Other damage"
See also: Get your iPhone, iPad, or iPod touch ready for service - Apple Support