Thank you everybody for participating in this conversation. I've waited to reply to see if I had anything noticeable to show, and well, the difference has been stark. They just don't agree. If the BD and GG#4 were a married couple, they'd have married in Vegas while drunk, then woke up the following morning, declared WTF?! and divorced.
First up is the Blue Dream always looked kinda yellow. Early there seemed like there was some deep blue in the veins so I thought it just might be the strain. But she grew slowly and got sicker over time.
So here is the Blue Dream progression, from sickness to health:
April 1 Blue Dream looking sick:

Here she is after I changed nutes from 1 tsp of Miracle-Gro Herb & Vegetable to 1/2 tsp Miracle-Gro Herb & Vegetable & 1/2 tsp of Miracle-Gro All purpose.
Here's how the NPK would look. I divided by 3 to show relevance to popular brands made specifically for cannabis:
Standard Grow Mix
100% Miracle-Gro® Vegetables & Herbs
Miracle-Gro® Vegetables & Herbs: 100% 18-18-21 /3=
6-6-7
Big Nitro Mix
50% Miracle-Gro® Vegetables & Herbs + 50% Miracle-Gro® All-Purpose Plant Food
Miracle-Gro® Vegetables & Herbs: 50% x 18-18-21
Miracle-Gro® All-Purpose Plant Food: 50% x 24-8-16
= 21-13-18 /3 =
7-4-6
Note here I call it, "Big Nitro", but there is also a significant decrease in phosphorus and a smaller decrease in potassium. Something else I think is significant, as things went on, is that the All Purpose mix contains ammonia nitrogen, which the Herb & Vegetable did not. That may have affected the chemistry, too. It isn't just about NPK, but all that ion stuff, too.
April 8. Here you can she she is sick, but getting a bit better. This is a week before the initial post.
And here she is on May 3 -- lush, large and two weeks after flip. Due for a trim.
Great recovery, huh?
So I started using that mix on everything, thinking I'd been missing out in other grows, even though I'd never had any problems before.
The GG#4 tells a different story. Here she is on April 9. Happy, growing, just been deci-folded. Something new for me and my lateral anchor stakes.

But, uh-oh. April 11. Did I miss some watering? Was my mix off? What changed? I'm just starting to wonder.
Things weren't getting any better, so I wrote my original post. Got some good feedback from everyone, thank you. Here we are on April 18, the day after the post. Stuff is bad! Time for action! It's never too early to panic!
So on April 23rd, I flushed the darned thing really heavy, trimmed off all the ugliness, and went back to the original nutes.
Three days later, on April 26, the recovery was in session. Things are looking better.

By May 3, she was fully recovered and growing like ... well ... a weed.

What looks like a small change was a big one.
Thank you for reading. I hope this helps others.
BR