The plant looks sick: What is it?

Few things wrong here, wind burn, root problems, medium could be drying bout to fast, get some soil food in there.. microbes , bacteria, some alfalfa meal or Vermicompost.... that fan is way too close.. Good luck.. Much love 💚..

Chronically over fed and suffering from nitrogen toxicity. It is NOT a nitrogen deficiency!!

Lack of N. Check our pH.

Hey there sometime you get a seed that is super sensitive to stuff like light and over and under watering also nutrients and humidity and temps It’s hard to say exactly what yours is sensitive to What I do to avoid this is always start like 4 to 5 times as many seeds as I wanna grow them the best 50% that sprout in a paper towel put those in soil then the best half of those that sprout out the soil fast and growing not deformed I use those. It ussally weeds out seeds that are finicky

wind burn. its the plant thats right in front of your fan. This can happen and the leaves are a tell tale sign of wind burn/

Since the others look fine, it’s likely early stress or weak rooting. Without more details (like medium, watering, EC/PH), it’s hard to be more specific. Tip: just keep observing, treat it gently, and avoid strong feeding. It might still grow out of it. You could also consider repotting or adding some beneficial microbes to support the roots.