It sweats because colored socks are polyester or have plenty in them. All cotton colored socks
fade and get pilly. And white socks
are mostly cotton or at least 80% cotton, and absorb what little sweat 2-20% polyester makes one sweat.
Or do your feet sweat or itch a lot from the shoes? These are reactions that come and go. But one thing is for sure folks. Plastic allergy is very real. Although mild for most compared to other synthetics, or higher quality plastics.