Canon is reporting instances of counterfeit EF 50mm f1.8 II lenses being brought into Canon service centres for repair.
While the exterior of the counterfeit lenses imitate the exterior of the genuine lens, the parts and electric circuits used inside are different from those used inside the genuine lens. As such, these counterfeit products do not satisfy the safety standards of various countries and the safety/quality standards of Canon.
You can read more about this, and how to identify the counterfeit lenses here:
Counterfeit EF 50mm f1.8 II lenses