Hello @Highclass! I disagree with everyone, in my opinion it's not a light stress. Rusty spots and edges on young seedlings may make look like a nutrient deficiencies or a light burn, but these symptoms are actually caused by a combination of overwatering and a too-small pot. As long as roots aren't happy, the plant won't be able to uptake nutrients properly, and will look weird/sick. You should transplant asap or you this might lead to root-rot and/or root-bound. Once transplanted, pay attention to your waterings, roots need to be on a wet/dry cycle to expand properly and stay healthy. Never water with more than 20-25% of your pot's capacity, and always let the medium dry a bit before watering again. Hope this will help, let me know in the comments section if you need any further information, and happy growing! 👊
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