I have had this before multiple times.
every time it was on autos as well. I have always related this to overwatering in my case as thats what other said it was. but I have had other plants from the same pack of seeds grow just fine in the same soil and watering amounts. I would try and lighten up on the watering just in case and keep nutrients low to no and give it some time to grow out. All of the seeds I had like this grew into full beautiful plants.
Good Luck!
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