and FWIW, off the top of my head, i can't think of any particular nutritional element likely to cause a rash of reproductive problems in your birds which wouldn't have much more noticable external symtops evident across the whole of the flock.
Excess fat certainly can cause problems, and there are plenty of very fatty diets out there for chickens (particularly coming fron certain youTubers), but there would be plenty of other signs of excess fat accumulation you'd likely notice before individual reproductive problems started to crop up, and those symptoms would likely be more closely associated with one another over time. Same with calcium deficiencies. Or selenium, or phosphorus.
Excess fat certainly can cause problems, and there are plenty of very fatty diets out there for chickens (particularly coming fron certain youTubers), but there would be plenty of other signs of excess fat accumulation you'd likely notice before individual reproductive problems started to crop up, and those symptoms would likely be more closely associated with one another over time. Same with calcium deficiencies. Or selenium, or phosphorus.