It means you have been giving them to much green color. That what’s nitrogen does.
When you are in a nitrogen toxicity your plant won’t be able to pick up the nutrients in the water. So the growth will be stunted
You have been giving you plant to much nutrients! Flush it and give it less a/b or veg in ur solution!
You have a nitrogen toxicity and can be quickly solved with a flush with low nutrient in the water to not chock the plant.
Search for how to get away with it on YouTube there is so much vidios out there.
(Nitrogen toxicity)