Looks like ph lockout to me. Def not light burn if there is even such a thing. I’ve seen bleaching from blurples too close but never actually burn...a singe-ing of the leaves maybe but your plants look like classic nute burn. It is also possible that too much nutrient has not only burned them but also caused ph imbalance; nutes w/high value NPK numbers can do that. Over-watering usually causes some issues but should not throw off the soil ph unless you are growing in a sterile medium without buffers like coco and are not ph-ing the water or nute solution correctly. The easiest fix might just be transplant into a bigger container. Then just plain old water for a few weeks...
To narrow it down its helpful to know:
What kind of medium?
what are you feeding and how much?