Well, we can fix this by using the fill setting in the GP material’s settings, instead of the stroke setting. Now, if you were to simply change the material of the existing GP points, it wouldn't exactly work. When you use a fill stroke, blender will fill all the space between the first and last GP point of a stroke, and since our stroke wraps around the model, the filled space would actually be inside the model, creating clipping issues again. Even if there are more GP points between the start and end of a stroke, these issues will persist.