Are your fans pointing directly on the leaves? That can dry them out

From the picture they look a bit brighter green at the top, which could be light stress. You could try reducing your light intensity and if it was light stress they'll go darker green pretty soon. If it doesn't work, just turn the intensity back up

Your leaves look over-watered to me, based on the texture and thickness. Over-watering is watering too often, as opposed to giving too much water at once. When the roots don't get enough air, the root hairs drown and you can see all kinds of weird "deficiencies," despite having plenty of nutrients in the pots. It will depend on your media, but if you're in something that holds onto water hard, I'd let them dry out until the pots are pretty light, then water slowly to runoff.