have you grown the strain before? you are certain this isn't just genetics? Can't really tell if its the color of the photos or what, but does look a little like there is a deficiency.
Wild ass guess (could be the lighting) but they look a little faded, and a bit of droopiness (which could just mean they need some water for the drooping). 30 days in mine are looking about the same flower development stage, but a much greener hue. These are 2 Bruce Banner autoflowers at 32 days from seed breaking surface. A lot of times uniform lightening or yellowing of leaves can be as simple as a nitrogen deficiency, if you post your soil mix, and what you feed, how often, and how much, you may get some more detailed help. Best of luck mate!
With coco, you want to have nutes every time you water. In coco or rockwool or any media that doesn't hold on to nutrients like soil, you really want to keep the EC stable. Plant relies on EC to maintain its internal water pressure aka turgor. When the EC changes too fast, the plant suffers, sometimes dramatically. The change in turgor resulting from the EC change can burst cell walls. Usually this is only visible by the stunted growth. Those blown out cell walls are also a great entry point for all kinds of nasty things too.
look close at your leaves see the green veins but yellow 'flesh' thats MgS04..calmag def, typical of late veg early flower How to fix Cannabis Magnesium Deficiency (Mg) Pics & Symptoms note the red stems thats stalled sap, too cold, the active sap stalls just like the blood in my granny's leg. keep warm 77f/25c next time post pics in normal light ..thanks good luck