Treat foods should be limited to less than 10% of the chickens' diet -- which amounts to a tbs or so.
Giving them free choice fat and carbs is like feeding kids on chips and cake.
A really good "treat" is their regular feed wetted into an oatmeal-like consistency. They go nuts over it.
Better to enrich the environment than offer fatty or carb-heavy treat foods.
https://www.backyardchickens.com/threads/a-cluttered-run.1323792/
Or, at least, make the boredom-buster treats something like a pile of garden weeds, a wedge of cabbage, a cucumber, etc.