Many thngs are hard to see at hatch and get worse with time.. this varus/valgus deformity being one of them and cross beak being another.. that I've seen.
https://www.researchgate.net/publication/6401121_Valgus-Varus_Deformity_of_the_Intertarsal_Joint_in_Broiler_Chickens
Thank you for the update.