yeah it could lead to light stress, honestly it depends on the genetics though. think of it this way, sometimes in nature there's a full moon which reflects plenty of light and somehow it doesnt kill all the cannabis plants. However a lot of the "high end genetics" like these kinds of seeds will have issues. what you do is use a bit of duct tape or something opaque and just cover the lights from the fan and the heater, works totally fine. Might as well check the seams of your tent or room aswell, anything with light leakage will be a problem so just cover them up. Hope this helps ! 🚀