Imo... but I am a newbie... it does look like nute burn. Do you as a soil grower measure either the EC/PPM/TDS. Also I was under the impression that it's not necessary to give new seedlings any nutes as apparently they come stocked as a seed with it's own self survival kit for couple of weeks. But again, I'm not sure when or when not to add nutes for soil.
Hope you get to the bottom of it
Grow 🌱 well
😎✌️🏼
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