Light Burn?

I agree with the other posters here. but all of this could just be from heat since its in a small container that container is super easy to heat over 86deg F and once that happens water and subsequently nutrients can no longer be taken up by the plant. That's of course not a problem if the heats only there for a few hours of the day. In that case, you'd just see some wilting... But if you combo that wilting with even a low heat CFL that's too close you'll quickly get burt tips like this. Id be sure to turn off the CFL when its in the window and I'd try to shade the cup its in from the sun so the dirt doesn't heat up as much. To fix this I'd let the cup dry out a bit before watering any and when you do water only give it a half drink with some super thrive (about 1 drop in 2oz of water) then the next day give her another 2oz with water soluble silica mixed in to boost the plants ability to handle heat stress. the just leave her alone till she shows she needs water again... You'll see her start to green back up really quick after the super thrive, like within 24hrs you'll see a difference.

Looks like a host of issues from heat, light, ph, and over watering…

Looks like direct sun damage from being in the window. Best of luck the rest of the grow.

if you didn´t add nutrients then i woud also say heat stress, raise it further away, and see if it still happens. Wish you best of luck mate🙌