Is this an Iron deficiency? The tops and new growth look too yellow and the veins are yellowing with a darker green in between

iron and other trace element issues are very rare. good soilless/hydro nutes have them included and soil has it baked in, typically. So, ensure pH is okay, which it looks like it is fine, and you can assume it's something else. Only a few things yellow from inside-out on teh leaves. Sulfur-defciency symptom is one that isn't a trace element. if in soilles it's a simple check.. are you providing 100+ ppm of S? if not increase S. in soil it's not so simple as you have unknown amounts of nutes in the substrate itself, so it's more trial and error and no verification to start, so it's more of a guess and hope for the best if not familiar with the products you use -- trends of this nature will be predictable with time and not a guess in future as you hammer it out. are the trunks turning woody? any purple streaks in stems? (not leaf petioles, just stems). these are other signs of S-deficiency. It's moving so slowly you can be patient. If unsure or find multiple possibilities, let it play out a bit longer to better differentiate.