hi buddy !! if u can take pics with natural light or close to is would be better in future 👍bcause that kind of light it is not easy to correctly diagnosis your issue....
imagine if a bad diagnosis is applied it could a worst remedy than your issue 😉 .....same a pic of the whole plant is recommended to clearly see if it is younger or older leaves or the whole plant wich are affected
so if it is the younger leaves firstly wich are much affected it should be a big N and magnesium deficiency...at least ...and yeah it could be caused by some lockout process but aslo could be other reasons.....if you were already a bit in deficiency in veg in N and Mg it is absolutely normal at this flow step👍
as they are mobiles nutrients if the plant needs them she goona suck the N and Mg in leaves to redistribute it in order to make more flowers...in few days if its not the case already.... big probabilities you will see some brown spots for calcium def wich is a semi mobile nutrient...
so add cal mag to fix that...
i can recommend you a big MO beneficials innocultation in you soil and near your main roots they can act as a bio regulator to break lock out processes if u have.....feel free to take a look here
growdiaries.com/diaries/28932-let-mother-nature-do-the-job-1st-part/week/140117 tricoderma got the habiltie to keep feeding the plant in N chelates so it can help to keep a good flowering processs
hope this can help....happy growing buddy 👊