Nitrogen Deficency??:/

Astart is right. The only probleme could be calciulm begening to run low. So feed it cal mag a little more since its in full flowering stretch and don't stoo nitrogen feed for atleas another month you can reduce slowly but for the first 5 week of flowering nitrogen become less and lees needed but slowly.. your olant look good.. youl be able to slowly raise the nutrient dosage. But ither then mild calcium the relatively very good. No burns, no bugs, its doing its thing. Few more drop of calmag to the solution mix and they'll be good

Most of that is just new growth and It's normal for new growth to be a bit brighter. Overall the color looks good with the back plant being slightly lighter but i believe most of that is due to new growth coming from the lower portions of the plant.