Certified GKH Gardening Expert
I think what you see is a condition called drupelet White Syndrome. It causes some drupelets on the fruit to be colored. They will be smooth though. Here is more info: https://www.gardeningknowhow.com/edible/fruits/raspberry/white-drupelet-syndrome.htm
If what you see is a fluffy mass, send us a picture. It can be a mold or it can be a nuisance, like woolly aphids, and we will only be able to tell from a picture.