Below is a quick video clarifying what to expect and/or what options you have when ordering wall cabinets. In most cases, unless a custom modification is requested, the interior of a wall and/or base cabinet is a natural melamine or vinyl wood grain finish that protects the plywood from water. Have a look at the video below. If you have questions let me know.
from https://nhkitchens.com/cabinet-bottom-and-interior/
