Nitrogen deficiency?

To me it looks like the beginning of nitrogen over dose, not deficiency. Having your bags with a low height of soil can slow growth, especially when young, as the seedlings do not receive any reflected side light, only light directly from above. It constantly amazes me that people want to grow the biggest plants they can, then only fill their pots half way, reducing room for root growth which then reduces pant size! The soil is the cheapest individual part of any grow and skimping on its use is pointless. Apart from these points, cold temps and poor lighting can also affect slow growth, but without a diary, it is hard to offer anything more specific. I assume if they seem to be flowering they must be autos, so it is too late to expect any great increase in size once they switch to flowering in earnest. This is the biggest problem with autos, getting them to a reasonable size before flowering commences. Cheers, Organoman.

I think you give too much water or you just watered. I dont see the other symptoms of too much water, the smaller growth can be because of: lights too close / too high, then they do not need to grow that high. If you see they start to flower, they can get too little light in hours, under 18 is not good. But I think its nutrient lock cause of overwatering. I give them only a litre maybe one and a half every three days in this stage per plant. Dont mind the earth drying out a bit this keeps them wanting and making new roots. As they grow I expand the amount of water and the area I put it slightly. I dont water all the growbag, if you look at my grow, the bags havent been wet, the entire time ive been growing. Try letting them dry and to be sure, next feed add some growfertilizer but only for 1,5 liters a plant. Maybe even one... Then only poor around the plant. Good luck!!