I believe if you are accustomed to looking at the tip of your arrow, consciously or subconsciously, dusk shooting can cause you to shoot off. I believe it's due to not being able to see the tip clearly in low light, and imagining the arrow tip is pointing more to the right than it really is, and overcompensating to the left.
I noticed this myself, and eventually cured it by making certain that I fixate on the spot I'm aiming, rather than confirming alignment by also glancing down at the arrow tip- That's what helped me at least.