@ Qurat .. It is normal only. No need to worry. Due to high moisture and also addition of nutrients (feed) some fungal growth is here. It will be automatically disappear.
No problem at all , they changes color such as white, black red and blue more often than the brighter colors green and yellow according to feed and moisture. Finally it will turn into black.
Michael Quintern We have made a recipe of C:N 32:1 and it includes
Coffee ground, Spent brewery grains, cattle manure, spent mushroom substrate, wood chips, straw, shredded office paper, shrub trimmings ang garden trimmings. I can also send you the recipe with the exact volume used of these products.