I'm thinking this might be a zinc or magnesium deficiency. I've heard these problems are often caused by pH lockout, but my pH was fine last I checked, a few weeks ago. I haven't done anything that would change that. Since this is a very conspicuous-looking problem, I hope someone knows what it is.
This plant is a Satori, and a bunch of my Hashberries have the same problem too. Interestingly, this is my biggest Satori by far, and the only one showing this problem.