Brown Spots on Leaves

Looks like a Cal/Mag Deficiency... https://www.royalqueenseeds.com/blog-calcium-deficiency-in-cannabis-plants-n602 also check ph of your solution i would guess. Ether that or you have to much of something in your soil that prevents the uptake of those two elements...(the tip of the leaves are aiming down a bit like clawing thats an indicator for to much nutes in the medium but that may just look like that from the picture itself also the leaf tips aren't burned witch usually accompanies that) Get some PH strips/stick some Cal Mag Product of your choice and that should hopefully fix that.