He is bugging his mum!
I don't know what DBSF is, do you mean dried bugs? (Soldier flies?)
They aren't as nutritious as the sellers make us believe. Just fancy (expensive) snacks.
It doesn't look like it is a symptom of anything bad, so that is a good thing... If it were mites or anything skin related you would see them/marks when you examine him.
If you have a macro function on your camera (or a kid's magnification thing like a microscope or a loop) you could take a closer look.
It doesn't seem bad... No other symptoms?
I have a hen who fights to be first in the food bowls, so she plucks the other hens' head feathers. Sometimes I end up with a bald hen

so not technically molting, but she does then have to regrow her head feathers.
Could they just be picking each other clean as a little bit of fighting?