While many strains lose their larger fan leaves during flowering, the yellowing usually begins at the bottom of the plant and doesn't cause burnt tips. I get as low as 15% Rh and don't have burnt tips like that, so I going to say that you have a nute imbalance, which is pretty much the same as a lockout. I would ease off of the nutes and give it a moderate flush, since it doesn't seem critical. The yellowed leaves won't recover but as long as new growth looks good, them you are heading in the right direction. Have you defoliated the plant? There seem to be few leaves on the plant, which are used to both create and store energy needed for flowering. With few leaves, there isn't much of a energy reserve for the plant and it could rapidly cause yellowing, although I don't think the primary issue is a lack of nitrogen (the most common reason for yellowing or light green leaves and growth).
Since you are close to finishing, it might be too late to do much about it since they won't grow many new leaves. Keep this in mind for your next grow and maybe go a little easier on the nutes. I grow with much less than most growers use and a ton less than manufacturers recommend, but still have great results. My philospphy is to try to recreate conditions it would find in nature... fertile soil is one thing but the amount of nutrients that are recomended for a small plant would be more suitable for a large tree... just my opinion from decades of growing.