This is a really interesting edge case. When they were talking about it in lecture, I never would've thought about this. However, once the image showed up, it immediately thought about the penrose triangle. I wonder what would happen if we tried to draw the penrose triangle using Painter's Algorithm (if we fixed the unresolvable depth order somehow)
The unresolvable depth order refers to the fact that when sorting objects, there may not be a definite ordering. This is because part of an object may be behind another object while another part is in front. The penrose triangle cannot exist as a solid object so I don't think it would be possible to draw using Painter's algorithm.