Layer feed is probably one of the most well-researched animal feeds on the planet. It's carefully formulated to be a balance between adequate nutrition and cost control. Protein is expensive, so they've calculated the bare minimum the majority of production bred birds need to produce, in a confinement operation where they don't get any other feed to mess with the nutritional balance and don't have a lot of exercise opportunity to burn off precious calories needed for egg production. It's perfect for what it's meant for.
Thing is, backyard flocks are different. We feed our birds treats, usually lower protein veggie or grain types, and that lowers the overall protein levels the bird has. Our birds have more space, so they burn more calories overall. We encourage behaviors like scratching and foraging. We also keep breeds that aren't production-based, but still want them to lay well and be healthy. We're also more attached to our birds.....if a handful of birds in a confinement egg operation don't do well on layer, no biggie to the operator. If one or two birds in a small backyard flock don't do well on layer, it's a big deal to the flock owner, both production wise and emotionally.
So, layer does have it's purpose. It's just not for everyone. I wouldn't return the bag, just buy a bag of grower. Or see if you can get something higher protein, like maybe turkey starter? I'm not sure right off what protein levels are of other feeds, but ask at the feed store. You can then just mix the feeds.