loosing chicks to bulling?

[nuthatched]

Ferminting 2mos ago. the grains oats, wheat, chipped corn, & Flaxseed. I add a large cup full of starter grow & black oil sunflower seeds to their food. & once a week I add red pepper flakes.

This is the very likely issue. This isn't nearly enough nutrition for them to grow and survive with. They're picking each other for nutrition.
They need nothing but chick starter for the first few months.