I don't know I don't have a PPM meter. I ordered one yesterday so will be here today. The others are way worse that's probably not the best pic to use.Doesn't look bad. In fact part of the leaf still looks functional so definitely leave it. How many ppm were you feeding? I wouldnt go over 200-300 with a seedling that size.
Post one of the bad ones if you can, they might be a lost cause. PPM is super important if you're going to use coco, its practically hydroI don't know I don't have a PPM meter. I ordered one yesterday so will be here today. The others are way worse that's probably not the best pic to use.