Could anyone help me with recognizing what's ...

Looks like a mix of nute burn, from too much potassium and phosphorus, and nitrogen deficiency. I don't see any nutes listed that you are feeding your plant so it is hard to say. Another thing that I don't see listed is the PH of your water you feed the plants. If you arent PHing your water you might be running into PH issues which can cause discoloration that looks like a few different issues at once. You want your PH to be around 6.2-6.8. If your PH is too far out of that range it can cause the plant to not uptake certain nutes and if the ph swings too drastically it can cause weird issues. I would check your PH just to be sure its not the issue. With either issue you are gonna want to flush with 3x the pots soil capacity in water(so if its a 5 gal pot use 15gal of PHed water to flush) to reset the ph and wash out any built-up nutrients. After that, if it is just a PH issue, make sure to keep PH within range. If its a nutrient issue I would back off on the P/K feeding and give every slightly more nutes with N in them.