Soil level looks fairly low for that size pot so I am leaning towards low-moisture/drought stress. I would add more soil until it is nearly level with the rim of the container, the plant(s) will slowly put out new roots along the main stem and keep the mositure level somewhat more stable and likely reduce the potential for root restriction. Can only help the final yield as well.
The damage to the leaves is also a little too widespread and consistent to attribute to "sloppy watering" under the lights.