Some of my models have a weird bug(?) where the 3D window will become slightly dim when I do not move the mouse. When I interact with the model or move the mouse the 3D window will become bright like normal again. It's really annoying for viewing since I don't continually move the mouse and the 3D window keeps switching from bright to dim.
Here are two links of models where I have this problem:
These are my most recent models, but this problem also now happens on some of my older models where it didn't happen before.