One of these not like the other

So my first grow and I’m heading into the final couple weeks and one plant is not looking so hot. You can see in the pictures. Very brittle dry leaves. Wondering if you think I should harvest that one even if it’s a little early just to salvage what I can out of that one and wait on the other two.

Potassium deficiency is potassium deficiency, no matter how severe it is.