Yellow leaf veins close to harvest what's problem?

2 weeks til harvest just started a day ago yellowing in between the leaf veins actually the vein itself is yellowing unlike mag def where veins stay green and rest yellows or is this mag too? On most fan leaves bad starting slightly on the rest of the smaller leaves edges are all slightly burnt also. Is this just the natural yellowing at end of flowering? if anyone can help diagnose thanks in advance.

Maybe a Zinc deficiency but most likely due to getting closer to the end of the plants life cycle sure it will still produce some potent buds! good luck man

Awsome thanks been feeding with AN 3 part series and cal-mag ph around 6.0 never had an issue until now week 9 today Fastbuds gc auto

Zinc seems to be mostly in beginning growth stages this is on older leaves

back off the ferts

Ok so is this what over ferts looks like after tips burn happened after I watered with plain PhD water or would of been first thought no mutes in week