OEM is the abbreviation for Original Equipment Manufacturer. In the past it was referring more to the original manufacturer of the equipment (product). This term is not only present in the world PCs, but also in the telephone industry, auto industry and others.
The problem of fake cables is old. Sometimes, fake cables are even marketed by large retailers. Buyers being generally very price sensitive, it is obvious that a cheaper version of a product will draw their attention. From bargain sellers on ad sites to some department stores, customers buy fake cables, enjoying the low prices, even if they regret their decision in many cases, when they find out that the product they bought is low-quality and may have a negative effect of the device they use it with.
Obviously, the easiest way to avoid damage from counterfeit cables is to use OEM cables distributed by IEC. These are designed to work with the devices they are marketed with and will not create problems. These cables can be purchased from the authorized distributors of the respective brands. However, if you buy such a cable from someone else, carefully examine the packaging and the cable itself and make sure it has the correct logo and brand name it was designed for.