Chickens can safely eat a little bit of quail food but since quail food has a much higher protein content than regular chicken feed then the chickens could be harmed if they do eat too much quail food.
The chicken feed contains the correct amount of protein and nutrients for chickens so it's best to feed the chicken regular chicken feed to keep the chickens healthy and growing properly.
But a little bit of quail feed is not gonna harm the chicken but if you feed the chicken too much quail feed then it could be harmful because of the overdose of protein.