I would say you are having some ph issues. Looks like a zinc or magnesium lock out or deficiency. What are your ph levels going in and coming out on the runoff? I would check these and check your ph instruments calibration as well. If this is all in the normal range of around 6.5 then try adding some cal-mag additive will probably help I think. Hope this helps, Cheers💨
Looks like a deficiency of some sort. I'd try supplementing a bit more cal mag onto your affected girl and she how she's responds. It doesn't look like it's happening to all your plants I'm guessing this phenotype just needs a bit more. 🤘😤