It’s too dry.
1. Water, 2 water, 3 water, it should be getting water 3x a day
2. Cal mag everytime, irreverent on water conditions,
calmag everyday
3. 400-500ppm max per feed, feed daily , some feed 2-3x just cut nutes down To aspect ratio for daily feed vs multi feed per day.
4. Coco isn’t soil treat it like hydro. . It needs to be wet, if not the salt buildup is fast mate.
5. Lights, up the blue spectrum in the veg stage. 3000k is not ideal, 5-6k is th ideal veg range.
Air flow, is critical, incoming fresh air vs exhausted , need to maintain that co2 in the grow space.
Humidity; though not critical at this stage but later on coco it’s harder to control unless you have that watering down to a science!!
Cheers and happy growing
Ps alternative to coco is high porosity soil media basically fine mulch with coco works like soil, less watering as it holds water but inert so feeding is about half rate and less worrisome. Look into that before trying coco out right. But in coco it’s basically hydro , do a catchment tray that drains to a bucket of sorts and you can recycle that water with a pump to water just change out the water every other day and you can set that pump on a light timer to feed/water every 6-8 hrs , then dump residual and mix fresh, fairly inexpensive to do really if you can source parts and are handy.