Is this a deficiency or light burn

Seems like an Iron (Fe) or Magnesium (Mg) deficiencies - Interveinal chlorosis (green venation and yellow foliage with tip chlorosis and blotching on older leaves. Try increasing your A & B fertilizers to about 3ml/l and check all of your fertilizers labels to see which one contains Iron and increase that by 50% (if it's either A/B/ or both then keep it on 3ml/l) Hope this helps! Good luck and happy growing :)