It's almost certainly related to overfeeding based on those pics. I'd be guessing at what specific nutrient is doing that though.

I'd rinse them out with plain water slowly and see where the runoff ec is at. It should be between 1-1.5ec.. If its higher than that rinse till its below 1.5. Then if they respond in a couple days start them back on 1/4 strength nutrients.. or get them transplanted sooner than later.

This is assuming your FFOF is actually depleted. How long have they been in the pots vegging for?

Thanks for the reply.. So, i got the clones march 8th and they went from their 4" baby pots, to 1 gallon pots with FFOF. I let them rock for a few weeks until they got some growth and nice roots throughout the pot. I then up-potted to 3 gallon pots, again in fresh FFOF. This is where i feel i may have made a mistake, because by transplanting into fresh ffof, the roots would eventually hit the new soil and be hit with all new nutrients, although i never had issues in the 1 gallon pots. I almost feel i shouldve used a more inert soil on the up-pot and fed nutes.. ANNNYWAY.. so now they were in 3 gallon pots, doing their thing, and i started noticing some light green new growth, so thinking they needed some food and decided to hit them with their first nutrient dose. I believe it was 1/4 tsp/G of seablast grow. Im a newbie, but i was able to recognize some nute burn on leaves that turned super yellow, brown and eventually died off. But this seemed different.. Especially since one plant has it going to the top of the new growth. It would be my assumption though that when i uppotted to 3 gallons in fresh FFOF, that it wouldnt be too much, since they were in ffof since they were baby clones.. I am assuming that i did indeed just dose them with too many nutes. Besides what i posted here, alot of my plants are a very dark green, and almost shiny leaves, while at the same time the leaves feel a little, lets say crisp? Like they arent burned, but they dont seem to have soft flourishing leaves. Over all, my plants seem healthy, and this isnt wide spread or on all of them. It sucks because i got different batches of clones at different times, so im trying to keep track of whats happenening with all the different cuts. For now im going to revert back to just straight water, and tomorrow i am going to measure the run off ph and ec and report back... The final destination for these all will be 15 gallon pots, in a greenhouse with some bulk soil amended with rainbow mix pro grow, and then my nute line will be the sea blast grow/ bloom. Im fairly certain they have nitrogen toxicity due to the very dark green and off setting texture of the leaves, so im hoping with just watering them they will make it through. Ill include some pics over all of all the plants, and see what peoples opinions are. Thank you for your reply!

ps... i started growing them in march because we intended to do light dep, so i was trying to get em to a nice size, but due to certain reasons we are going full term, so im almost nervous they are going to get too big for the greenhouse, but with that being said, they have been vegging almost 2 months exactly as of this posting.