Backyard Aquaponics
A place to discuss aquaponics

While it's possible that high growing temps along with high intensity light could cause this or contribute to it and it's also possible the plant will grow out of it on it's own or that this is normal for some types of pepper plants, I think this is a calcium deficiency and I think spraying is your best option.

I can tell that some of the plants have longer internodes in spots, maybe because of the change in lighting.