Leaf edges pointing up?

Lower your light. Looks like they are stretching up too much too early to get light.

Sieht so aus als hättest du sie übergossen, ist mir auch schon mehrmals passiert

Hi! Seedlings likes very humid conditions and I think that might be the reason. It does not look that bad tho but if you can you could try to raise humidity to 65-70%

looks like heat, but your environment eliminates that. Chalk it up to a young plant, i guess? The first few sets of leaves don't always give the best representation of what is to come. as long as you only use the values under this particular light, a lux meter / cheap light meter can tell you relative intensity. Distance from light will be consistent in this respect too. Inverse square law applies. Learning some klux values to adhere to is a heck of a lot less math in your head :p But, they won't translate to other lights unless same exact spectrum and whatever other aspects required - safely translateable with same diodes, temp, cri etc....