yellow stains on my macbook pro 2017

hello everyone,

Im having yellow marks and stains all over my Macbook for some reason. They are visible sometimes and sometimes they’re not. Im sure that my mac book is out warranty so i cant get it changed for free but I'm not sure if its really my fault. i've seen other posts about yellow stains on mac book pros.

i think its apples faulty design because i didn't damage my mac.

Is there anyway i call fix this by myself?