The section that is darker in the pic was last. As best as I can speculate, the final layer started on the upper right corner. The slight visual texture hints that this corner was slightly deformed, likely barely lifting, but not a real issue. As the monotonic passes cross the cube in the area that appears to have a matte finish, the end overlap where the pass doubles back on itself is telling a story. The first half of these passes towards the upper right side show no signs of bulldozing or build up. As the layer progressed towards the lower left, more and more materials built up on the end overlap. (Note: g-code used in most printers does not handle the zero point of doubling back on a pass very well. It is a compromise/estimated type of calculation that determines how material is extruded.) The build up on the edges increases as it progresses towards the lower left corner. If you look carefully, you can see where the nozzle dragged from this lower left corner to the section with a rough gloss.

I hypothesize that the strange divot looking spot in the lower left corner is from the nozzle making enough contact to either partially lift the print (more likely), or caused the X or Y to slip a step. Either way, this would explain such a different in texture and IMO it is supported by the evidence I can see and interpret.