How big is your coop/run setup? Any very large breeds or bantam breeds? What are you feeding? Sorry for the questions, but needed to figure out how to help.
All have perfectly normal tails, but not the typical tail feathers. Most with this feature are males and culls. Once plucked, they look no different from their tailed brothers.
She's not rumpless. She's just missing normal tail feathers. It's been popping up in my line of Easter Eggers, originally sourced from Ideal Poultry, for a few years. I'll go snap some pics of them. BRB.
It's not a typical trait of hatchery sourced birds. It's more typical of a hobby breeder adding in something with a rose comb to the lineage. The pea comb gene is linked to the blue shell gene. A cushion comb is the result of the pea comb combined with the rose comb gene.