Would be good to give us the full rundown on your grow area pH , ppm , nutes used so on it will make it easier to help the last one with leaf margin up turning is to much light maybe raise up your light it's causing heat n light stress .

Sorry for lack of info i am adding now.

Seedbags
50Soil/50Perlite mix 0,4L square pots (with lots of holes under)
Using Flora trio @half dose.
ph 6,2-6-8 . Idk the ppm

Also have 400w DIY CoB Leds without lenses or reflection. It may cause this? Because i dont think all areas get same amount of light, or maybe this one get directly i mean too intense. Even all of them 48cm away only 3 of them curling.

Top pic looks like signs of early calcium deficiency but you shouldnt be deficient this early in. If it progresses then i would say its most likely calcium deficiency, but truth be told i wouldnt worry too much, its very minor, please the plants still look great considering, you shouldnt really too much when you see any problems, because problems are more then likely going to happen, you should only really worry if those problems progressively get worse.