If a hen was fed only fruit, I could understand where it might affect egg laying because they have no room for or no access to higher protein foods.
My birds are too young to be a test case, but in my childhood we fed a lot of surplus fruit and veggies and I cannot remember my parents ever commenting on a reduction of eggs.
I feed all manner of garden and orchard surplus, figuring it helps reduce the food bill and cannot hurt the young birds to have a varied diet.
but that once the fruit starts to fall (and rot), they tend to move the hens out of the orchard, because eating a lot of fruit causes reduced laying.
Easy explanation. What time of year do apples start to fall and especially reach the point of rotting? Fall. What time of year do chickens start to slow down laying? Fall. Does anyone see a correlation? It has nothing to do with the apples.