What’s happening to my plants?

It seems like leaf miners, and it’s caused by a lot of bug species like flies, beetles, sawflies, moths and others. It could be controlled by removing damaged leaves before larvae comes out, and most important is to prevent by using neem oil weekly, misting well the leaves when lights are off.

Look at the damages. Looks like the tracks of something ramping like a snake... So, on a leave... A larva ;) Eggs will became larvas that will take part of the buffet too. And then turning to flying bugs that will.. drop new eggs. You can use Neem oil or/and black soap as said by @ttrichome. That's a not damaging, and bio solution. Neem oil is mainly repelling insects, when black soap will mainly kill them. Depending of the amount of damage, if the situation is still under control, your plant not too big, you could still try to clean it by hands, meticulously. Removing eggs, larva. And daily check. That's what i'm doing on my current first plant : She spend 8 hours outside everyday. My garden is full of life, lot of insects... But so perfectly balanced. When i put the plant back home, I do a daily check, and remove any thing that may be on the plant with tweezers. So... One or two insects isn't a problem. The no competition between species and the big development of one of any kind is. I personnaly think (but that's a believe, just a feeling) that plant can be boosted by the little stress of one or two bugs. Because the plant have to react to this. This ask here a bit more energy. And I believe that it improve her "energy" production and use capacity. It's only a matter of loss of control resulting on too much of something (like a stress) that will get her weak. Just my own opinion here ^^ Good luck with her :)

I'm not positive on exactly which insects are doing this. A Neem oil solution with some insecticidal soap to help break down the oils with the water will work wonder on your girls to keep them pest free and shiny to boot! Just make sure you don't use it during the last 3 weeks of flowering! Cheers and happy growing!

That's damage from leaf miners. Neem and insecticidal soap can be effective to kill em.