Heya! First time grower here. I have a clone thats...

Adding sugars to a nitrogen-toxic medium can help stabilize it by balancing the C:N ratio. Just don't overdo it, small fractional feedings work best. Microbes tasked with breaking down the excess carbon consume all the available nitrogen, and they can pull additional nitrogen from the surrounding soil. This process, called immobilization, can temporarily deplete the soil of nitrogen, causing a nutrient deficiency, in this case, correcting a toxicity. Or flush. Just know that if you are flushing organic nitrogen, it takes 4-5 times more water to remove it from soil particles than nitrates. Best of luck.

That my friend, is an excess of nitrogen. You would do well to flush her (meaning give her twice it's volume in water and let it dry out) then hold off the feed for a while. It's not the end of the world, and if you correct the feed, she'll stay growing as expected again very soon

Came to say the same as Nocone - too much N right now

Looks like nitrogen toxicity, buddy those dark, clawed leaves are the classic sign. Check your feeding strength and maybe give plain water next time to let the medium balance out. Also make sure the pot drains well overwatering can make it worse. Once the new growth comes in lighter and flat, you’ll know it’s recovering.