N deficiency is another yellow and is in grow stage, in flowering you can have easy P or K deficiency that are the elements that the plants eat more. Buy a PK booster and give the plant 1/2 recomended dose or less one time and water 3 times after and then u can repeat if u want and u can do it before if needed with maybe 1/4 dose max.
Maybe some drops of calmag will be the top dressing, i love the biobizz one, very low cost and beautiful product, no N inside .
Pk boosters there are a lot of product out there, make sure that not have N inside and to give the recomended dosage ( mine recomendation related to their)
Hope to be useful and comprensive ✌️🏽