Hey OS_Farmz!
That's a tough spot. At 4 weeks, those two are definitely stunted. Since you're in coco, flushing with plain water usually makes things worse because it strips the buffer and causes lockout. Those pale tops are screaming for nutrients and Cal-Mag.
Try this:
• Stop flushing with plain water: Coco needs constant nutrients.
• Light Feed: Give them a light, pH-balanced (5.8–6.0) feed with extra Cal-Mag immediately.
• Check the new growth: If it stays yellow, your pH is likely off.
If these are autos, they might not have enough time left to fully recover. If they're photos, just veg them until they find their rhythm again. Hang in there!
Happy Growing, Growmie!