What should I do to stop the yellowing and the cra...

Hey there Gab ! Yeah it's a problem indeed ! What's happening is that you've got a soiless set up but you're not running enough feed. Soiless means "inert" means there's nothing in it, means that you have to give it 100% of the food the plant needs. Usually in coco you want both parts of the coco formula ergo part A and part B, and yes it's annoying that you have to buy two things but you do basically... nothing to it. You plants will still lack micronutrients so you do need to add specialised micro nutrients like calmag. Finally since the medium is inert, that means there's basically "no bacteria" to break down the nutrients, so you'll need an appropriate chelation agent such as amino acids, humic and fluvic acids, enzymes or simply hydrochloric acid. So when the medium is soiless like what you're doing you need the three categories of feed every day : the NPK nutrients of the 2 part formulas, the micronutrients eg calmag and the chelation agent. Right now you're showing deficiencies even with Nitrogen, that's because the lack of nutrients and chelation agent has caused root problems, you can tell from the downward clawing of the leafs. If you add a chelation agent to your feed it will break down the problem roots and the plant should recover within two weeks max. Hope this helps my friend ! 🚀