I Got Chicks From Tractor Supply (I need help)

For context, this is the fourth batch of chicks that I’ve gotten so I know how to raise them but this is the first time I’ve gotten them from Tractor Supply

One of them sadly passed away last night (light Brahma hen) and I was wondering if anyone else has gotten chicks from Tractor Supply that suddenly get very lethargic and end up dying with little to no warning or if I was doing something wrong. The rest of the chicks seem fine.

The other thing is the breeds. I got two light brahma hens (I only have one now) and I got two Sapphire Sky hens (I still have both)

One of the Sapphire Sky hens has feathered legs though so I was wondering if she happens to be a different breed?