Hi @Matt308 and welcome to OG
It’s really hard to tell from these pic and with limited information but this certainly could be caused by overwatering. One sign I am not seeing is dropping which almost always accompanies overwatering. Your soil looks very wet in the pictures so either way I would let that dry out somewhat before watering again. Other common issues that would cause this sort of damage are:
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Nute Burn - what type and strength of nutes are you feeding? Baby plants don’t need much so even small amounts can damage them
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Water or Soil PH - this one comes up all the time. What’s your waters PH? How do you test it(how accurate is your meter)? What is your run off PH? Have you done a soil slurry test?
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Root problems - I notice you are growing in styrofoam cups, how is the drainage? There should be lots of holes in the bottom for water to drain. Can you re-pot in slightly larger container with better drainage? This would also offer you a chance to check your roots visually.
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environmental- how far are your lights from the plants? How high are the lights set? is it too hot or cold in your room? Does the temp drop dramatically at lights out? What is your humidity?
look at all of these areas and I’m sure you plants will be bouncing back in no time. This biggest part is don’t give up, they can almost always be salvaged for a good harvest.
Cheers,
Loggershands