How about overwatering, maybe? When my plants look like that it's usually a water issue for me and nothing else.
You may want to provide more details on soil and what you have been doing for watering and feeding, so others can try to help.
You mention lights but we don't know par your giving so we won't know if too much light. From pics doesn't look like it as no canoeing but if in doubt on light par you should be getting a cheap uni t wifi lux meter and free ppfd app, you need both. This should be a known if at all possible for cheap and it is possible. You can back off lights as well , less light, the less plant is uptaking, your giving yourself time to see before dumping nutients in or flushing or doing something else not needed
