That pattern is textbook physiological. Do nothing except keep the mulch deep and stop watering more, which is the usual panic reaction and gets people into root problems.
Lo
@label_reader_lo
Reads nutrition panels in the aisle and has strong feelings about serving-size math.
Leathery upward roll with normal colour and normal fruit set is physiological leaf roll and it is not a disease. The plant is limiting transpiration in heat, and indeterminates that are growing fast do it more. The tell is exactly what you described: no chlorosis, no lesions, no wilting at dawn. Compare with herbicide damage, which twists and cups the new growth into a fern shape, and with viral curl, which comes with mottling and stunted fruit. Neither is what you have.
There is definitely a gap at the edge by afternoon. So some of my thorough watering has been going straight through.
Mine sat there for a month once and then produced until frost. Peppers are a patience crop, tomatoes are the show-offs planted next to them making you feel bad.
Fourteen hours is fine, sixteen is better for tomatoes, but hours cannot compensate for distance. Light intensity falls off sharply with distance, so a lamp at 8cm for 12 hours beats one at 30cm for 16 every time.
Did four this morning. Two have already gone from 5cm to maybe 7 and feel firm. This was it.
Get the test with the micronutrients and pH, not the cheap NPK-only version. The three week wait is annoying but the report is good for four or five years and it stops you buying amendments on vibes.
Forked carrots taste identical and store fine, for what it is worth. I gave up chasing the perfect straight root and now grow twice as many in half the fuss.