It's hard to describe my problem because it's kind of mysterious, but I hope with my description, I would be able to find some advice and answers here.

I have a open wardrobe, which means well, it's open, bought it from IKEA, so I hang my clothes on a hanger and just leave it there, and over the months I've noticed some kind of very small tiny yellow dots on my clothing, apparently it'll appear on some clothing not all, and on very small part of the clothing.

It's made up of a few yellow small dots, and when you wipe it off with hands and/or a damp cloth, it'll turn into stains, but it can be wipe out very easily without much effort. So, I'm wondering what could this be ? Please refer to picture below