its def a nute deficiency. im not sure exactly which one but the way that the leaves go from light green(in the center) to a darker green(on the edges) is clear indication. what kind of soil and nutes are you using?
Can you provide more information? type of soil, lights, feeding schedule, type of nutes, pH going in and pH runoff...
It has soil that is 40% peat I'm Using terr Flores vegger and it is under a 120w led light Should I hold flowering off until the leaves have returned to normal ?
You are over watering. The roots are not getting enough oxygen when they are constantly sitting in damp/wet soil. Water only when the soil is almost completely dry. Try every 3-4 days. Water enough until you get about 15% of runoff.
drilling many holez in the side of the container will get more oxygn to the roots. set an oscillating fan near them, and increase ambient temperatures to get the dirt to dry out faster. Also looks like a soil health problem.