What could it be?

study one spot on your plants and look to see if you can see any almost microscopic crawlers (aphids) on your plant. Also check the underside of the leaves for white spots..check the soil for root aphids. fungus gnats dont mess up your leaves like that. must be that or you are not waiting for the soil to get dry before watering. Overwatering will kill a plant and its the mistake i made on my first because i had OCD about it. Just be patient and the plant will tell you what it needs. In the plant world , more isnt necessarily better all the time. But ya pests, or watering practice. That or transplant shock.

Hi there They look abit over fed.. give them just water the next two feeds then cuts the neuts down a tad .. maybe add a small amount of calmag to sort out the calcium side of things Best of luck 🌱

same as last time, your soil too rich or you just bombard them with nutritions and bad ph