I had the copperhead lights at that height at the suggestion of another person with those lights.
At the same time in another tent was running another manufacturer's lights at the same as a comparison. All else equal, the plants under the copperhead light were not performing as well as the plants under the other light.
So, lowered all lights to the same elevation of 30" above canopy.
No difference in performance, the two still lagged and began to shape up as midgets. Everything on those two plants are miniature versions of plants under the other light.
Changed out the lights over the midgets to the same as the others. Trimmed the old crusty foliage off of one midget and left the other as is. They are all auto flower of the same batch of seeds from the same breeder. Since the midgets are already fucked up, figured what the hell might as well experiment with defoliation versus not.