The black foilage problem on my RGB mouse

[IsTheLMN]

I have been using my RGB mouse for a couple of months now. In the first few months I noticed, that there's some sort of black residue on my hand. Over the time there was more residue and you could see that the foliage from the mouse was flaking off, exposing the transparent shell underneath it. Then it was clear to me, that in fact, the residue was coming from my mouse. That shouldn't actually happen on a mid-tier mouse (paid about 39€ or 42 USD). It was clear to me that in fact, the residue was coming from my mouse. I thought it might have something to do with my hands itself, since they are often sweaty after being about 3 hours on the PC which then could result into the foliage coming off. But now, let us come to my question. How did that happen in the first place and how do i prevent it from happening in the future?