m0useanswered grow question a year ago Maybe some water got left on the leaves and it burnt a bit.
Water droplets on leaves and bright LEDS act like magnifying glasses and burn the plants.
It also looks like the start of Ca issues but you feed is acquit in calcium.
Any reason your growing on 12/12 in veg still? you can do 18/6 and then switch to flower when it is ready and mature. I don't think your plant is mature yet, I do not see any signs of pistils meaning its ready. It will still grow under 12/12 till it becomes mature and then it will enter flower, just less energy then 18/6 unless your matching the DLI from 18/6
Good Luck!