Leaf problems

I think two things are happening here: calmag and potassium deficiency. Now the question is why this is happening; it could be due to two variables. 1_ You're not feeding enough of each thing, which shows deficiency. The solution would be to feed more of these elements, and it should be resolved (it shouldn't progress further; the leaves will stay like this). 2_ (what usually happens) a nutrient lockout due to an excess of some other nutrient that blocks the proper absorption of these two that are causing deficiencies, generally in my case always related to an excess of nitrogen that blocks these. So, in this case, you should only feed with water and a lot to wash out the salts that remain in the substrate, and after at least 1 week, feed only with these nutrients and remove nitrogen or significantly reduce its intake at this moment. During flowering, nitrogen should decrease but not necessarily be completely removed. I see you're making progress in flowering anyway; I wouldn't worry too much at this point. From what I can see, you're close to harvest, maybe. Leave nitrogen aside, and if you're close to harvesting, just use water to clean the salts from the plant. Cheers, good luck!