This is something that Apple wants you to be aware of and with the iPhone 11, 11 Pro, and 11 Pro Max, it seems that it will be capable of displaying warnings and notifications to users if it detects that a non-genuine Apple display has been installed on the phone after a repair. This was revealed in a support document posted on Apple’s website where Apple warns about the potential issues that could be caused by non-genuine displays.
According to Apple, “The iPhone display is engineered together with iOS software for optimal performance and quality. A nongenuine display might cause compatibility or performance issues. For example, an issue might arise after an iOS software update that contains display updates.”
That being said, in the past Apple has been kind of resisting the idea of third-party repairs, but more recently the company announced a new program that would give smaller repair shops access to genuine parts. They will also be providing the necessary training needed to repair iPhones.