"Permanent discoloration" refers to a condition where something loses its original color and cannot be restored to its previous appearance. It means that the change in color is long-lasting and cannot be reversed.
Full definition
Prolonged exposure to spills, including food, water or other liquids, or to oil and grease splatters, can
cause permanent discoloration or damage to your cabinet's finish.
This occurs when a display suffers from
a permanent discoloration on any part of the panel.