Apple encourages users to opt for product repairs only from an authorised centre. Now, the guidelines particularly apply to the new iPhone 11 lineup for display repairs.
In its official support page, Apple stressed that if the display on any of the iPhone 11, iPhone 11 Pro, or iPhone 11 Pro Max is repaired from non-Apple repair centre, a message will appear saying, "Unable to verify this iPhone has a genuine Apple display".
While it would not affect the ability to use the iPhone, it indicates that the display is not genuine. Apple also said that non genuine display parts may cause degraded multi-touch performance or display brightness and colour issues.