Leaf color problem

I love how one person states --deficiency, while the other thinks it's excess. Flip the coin; heads or tails, if it's tails, double potassium, heads and cut it by half 😜

That's a nutrition burn with the looks of It. You'll never get them leafs green again but try reducing your nutrition intake on the next feed a little.

Looks like a potassium deficiency. You cannot make the brown turn green at this point, but new growth should be green if you fix your problems.