Freezer burn is a phenomenon in which the surface of meat turns whitish after several weeks to several months of frozen storage.
This is the "sublimation" of water, a phenomenon of evaporation that occurs below the freezing point, due to the direct vaporization of ice crystals on the surface of the meat.
After the water evaporates, the surface of the meat opens up with tiny pores that scatter light and give it a whitish appearance.
The surface of the meat is essentially a freeze-dried thin layer of meat, which accelerates the oxidation of fat and pigments (frozen smell) and reduces the firmness and taste of the meat.
As a countermeasure,
(1) Wrap with plastic wrap to reduce contact with air as much as possible.
(2) Perform rapid freezing to freeze quickly.