She is about 4 weeks old.. just moved to 7g pot. C...

The plant is underfed, my friend, at 4 weeks old she needs to be feed, she's looking this way because she isn't intaking any nutrients and it's affecting her growth and causing the plant to basically cannibalize itself. Hopefully, I answered your question and remember Happy Growing and Free your mind one puff at a time.

Problem is overwatering. Or lack of oxygen to roots... I would also say imbalance of nutrients/PH due to the mixture of medium you chose at a young age it’s better to just stick to one to start the seeds in like just Coco or just Soil... then transplant into you mixture of Coco, soil & perlite. It’s easy to stunt them young like this, but is easy to recover from too so don’t loose hope. Is everything premixed bagged products? Did the coco/soil come from a bag? It’s useful to work with a ratio 60/30/10 soil/coco/perlite? Or did u just guesstimate? Never the less you should always be supplementing calcium and magnesium. You need to let them roots dry out, you could probably go 2 weeks without watering! At this stage only spray feed. And Only do that every 3-5 days. You need a mixture of CalMag (calcium magnesium) and some sort of seaweed extract Kelp is perfect Rhizotonic is great for issues like this. Spray before lights on, then don’t spray again for at least 3 days. Let that soil dry right out! Good luck