Sorry for your losses!
sometimes chickens just die, unfortunately. We just had one die in the run (age 5 months). Although we don’t know why, it was shaped differently from its hatchmates (same breed). So, I’ll guess internal issue that was there before hatch and became unsustainable. We’ve had a couple others get injured and die from infection (despite treatment). Etc..a few more have died, but no other birds were sick, so we don’t have a known reason.
source: try a local source, or hatchery. We simply googled “hatchery in Ohio” and similar phrases to find a hatchery that is within driving distance of us (about an hour). Some people believe in hatching only eggs from hen older than a year, so they are fully developed and egg laying is sorted out with normal sized eggs.
Of course, keep in mind that you don’t want to get rid of your chickens, so it is important that you only buy females or have a separate (out of sight) area for the males to live.
good luck!