In organic living soil, pH of 6.7 in the pot. Not happening to any of the plants around her. Just looking for inputs.
It is mainly on lower, upper leaves aren’t as bad but seem rubbery. Could be a lockout than.Yes, it does look like K deficiency, BUT it may not be.
Do all the lower leaves have the symptom, and it gradually disappears on the leaves above it? If so, it probably is a K problem, though it may be lockout rather than a deficiency.
If all the lower leaves do not have the symptom, but only leaves getting direct light from your LEDs, it's light burn.
I can't tell from your pics which it is.