Are the roots brown at all? If it happened right after you moved plants, I wonder if they possibly are affected by root rot, since that seems to happen more often when roots get disturbed, especially when they're young. Did you also change the reservoir water? Could the roots have been damaged in the move? How are the other plants doing (the ones that got moved out)?
Can you post a picture of the roots (without moving them as best you can)? I know you're using Hydroguard which normally prevents root rot, but I figure we should cover our bases! The smaller plant seems basically fine, I wouldn't worry much about that one, but the other plant is freaking out like it's very unhappy 😒 To be honest, I've never seen quite that response before. But there's only so many things the plant needs, so we just need to figure out what's missing. Its possible it somehow got shocked when the composition of the reservoir changed. If that's the case it may just need time and TLC.
Can you post a picture of all your plants in their setup under the grow light? It's great to hear your other plants are doing well! But I also know that it's frustrating when just one plant is unhappy. You know you're doing something right because every other plant is fine!