When this was brought up before, it was referring to custom CPU and GPU cores like we see in other chipsets from the likes of Qualcomm, Apple, and Samsung. (xda-developers.com)
Those with other chipsets should be protected by macOS and OS X updates that were rolled out back in January. (cultofmac.com)
MediaTek MT2601 SoC is claimed to have 41.5 percent fewer components and lower power consumption compared to other chipsets available in the market. (techone3.in)