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.
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.
Sounds like nutrient problems. @MEGA956 pointed out the purple stems. Any possibility you over did it with calcium? That could lockout P, K and Mg, as well as others.