Looks like a bit of nitrogen toxicity or slight overfeeding, The downward curl (clawing) usually comes from too much N or high EC in DWC systems. Try lowering your EC to around 0.9–1.0 for a few days, keep your pH stable around 5.8–6.0, and make sure there’s plenty of oxygen in the reservoir. She should perk back up soon — leaves still look nice and green, so you caught it early