overwatering -- you dump so much water through the medium it drowns the roots -- if drainage is fine it is a temporary issue. Watering too frequently -- rootzone can go nuts with rot and other issues.
Don't over-complicate watering. I'm assuming you ar in soil, but the method is similar no matter what. Water entire substrate every time - this is where i bet you and most others are making their mistake. Water entire thing. Ensure there are no dry pockets. Wait for top 1" to dry and repeat. Simple as that. In coco your trigger to irrigate is a bit 'visually' sooner, but same loss of weight. The top will dry faster, so the moment it starts to change color or even just before, you irrigate.
with soil, a little runoff is fine. if you think soil concentration is ever too high you get a little extra runoff to combat that. In soilless, you always water until 10% runs out the bottom. This is integral to how growing in a soilless medium works - very important.
See how simple that is? if any of that sounds different from what you are doing, your watering habits have contributed to what you see here.
It's better not to water right before the lights go out, but if the choice is potentially wilting plants by the time lights come back on, you water them. Transpiration is very limited at night with closed stomata, so very little drinking occurs during dark hours.
If you were watering poorly before and not ensuring the whole thing got wet, you likely have a situation where the top half of the soil remains wet and the inner portions are drier. this is the opposite of what you want. roots will grow upward and any roots in the lower areas will die off if it stays dry for too long in any particular region of the medium.
Look like might have some imbalance in feed, but one fix at a time and see how it impacts anythign else you see before doing more -- anytime you are afforded the opportunity to be patient.
Light is another concern. if giving too much light per day they will be droopyAF for several hours at the end of light cycle. Drooping right before lights go out is fine, but if they are sad looking for multiple hours at end of light cycle, probably light-related. Read up on DLI (daily light integral). 35-40 DLI is a good starting target, but then you have to read plant and adjust from there. The variables that result in a local 'max' dli vary by garden.