As a word of encouragement, albeit the growth is slow, your clones look healthy enough. I think you have a handful of issues going on right now:
1. webs/white dots. Possible spider mite infection. This will completely stop growth on new clones and end a grow. There are many ways to fight them, search will help you find your answers to that. be conservative with your approach to treatment, you have babies here. they can't take adult plant treatment yet.
2. light intensity is too much still. dial those dimmers down.
3. temps seem a little suspect. I'm curious what your nutrient solution temps are more than what ambient room temps are.
4. humidity can be bumped up and maintained higher. this is in a balance with temps.
5. ditch the timer and run the lights 24/0 until you get something more reliable. your lighting schedule is NOT good for this stage of life. Coming from clones, it's very possible they're flowering.
also, just out of curiosity @Fro5ty , what is your native language?