This came to my mind after I saw that enemies are surrounded with just a red square, some sides of which vanished depending on the angle at which the camera was facing them, on low-quality settings, like on that screenshot with a gecko stiuck inside the building with no doors.
At times it wasn't a full square but rather L, Г, П or U-shaped lines (in fact, it was pretty hard to capture a screenshot where it was a full square, because even teh slightest movement of the camera made one or two of the sides disappear).