Plants blowing out on the bottom with yellow and dried up leaves

My plants have been yellowing from the bottom up for the past month and a half. The tops are fine but the bottoms not some much. Anything below the screen or deeper inside has dried up and browned out. What is causing this problem? The busier Gorilla zkittles held on the the bottom much better than the Chimera 3 and White Truffle. They were all four clones. Here are the pictures from a week ago. I will get some close ups tomorrow to add to the post. I know there isn't much I can do this season, but I want to learn and be better prepared for next season. thanks for any help.

There will be some fading of old shaded leaves. Yours look fine . Any serious deficiency will show up higher on the plants. Work more on your soil this winter and consider a mulch or breathable soil cover to keep plant lowers separate from grass/ soil contact.

They did the single leaf reveg in mid to late June. Then they did what I call a super crop with an explosion of compacted stem growth around the tops. I figured this pulled all the nitrogen out of the bottom of the plant and it started throwing out the bottom in July. I do see a few leaves in the tops that have yellowed but not many as of yet. I may hit them with some kelp for help. hahaha thank you. I will also amend heavily over the winter.

Wherever you aren’t getting adequate light, the plant is likely to eat it up sooner or later. I’ve had some branches crowded before pruning turn colorless. Literally snipped off albino looking branches in veg.