Yellow veins

Everything is fine Here. Keep your track

Could just be genetics. Your leaf looks healthy. I do see a touch of something on your leaf edges right at the tips. Keep an eye on it, but overall i think the plant looks healthy and there's no real concern. Yellow veins aren't a concern like chlorosis and necrosis are on the fleshy part of your leaves (between the veins) Careful using distilled water as that can cause wide pH fluctuations, which can cause damage to your plants. I just use tap water. It doesn't say if you are using Coco or Peat. They are pretty different from one another. I'd just stop using distilled water and stick with tap water. Follow your nutrients feed chart if it has one, and if you do run into issues, usually it's either lack of nutrients, or too much nutrients, or pH is out of range. So far i think you're doing ok. Keep an eye on those leaf edges though. See if it increases or stays the same. Feel free to PM me if you have any further questions or run into problems. Usually if shit hits the fan, flushing your plant with pH balanced water will flush out the problem, but i wouldn't recommend doing that from what i see.

I did some Google searches and seen many answers. It could be natural progression of plant one said. I do have a link to a post of someone who's plants looked identical to yours right now. It was right after he transplanted into a bigger pot. He topped off with some fresh soil and then did two half strength feedings. He stated they looked way better after. The post was here https://www.cocoforcannabis.com/community/the-soil-section/red-stems-yellowing-veins-lower-fan-leaves-only/ Again, mine did this and didn't get worse or cause issues. I yielded well. Goodluck growmie

I don't have the answer. Mine did this as well and nothing was wrong. They harvested well. 24oz off 5 plants in a 4x4. Sorry I wish I could tell you what it is though.