The latency numbers of displays ie the 8-9 or 40ms include any framebuffer the display might or might not have. If it is less than the frame time it is safe to assume it’s not buffering whole frames before displaying them.

Your GPU has a frame buffer that’s essentially never less than one frame, and often more.

And sometimes less, like when vsync is disabled.

That’s not to say the game is rendered in from top left to bottom right as it is displayed, but since the render time has to fit within the frame time one can be certain that its render started one frame time before the render finished, and it is displayed on the next vsync (if vsync is enabled). That’s 22 ms for 45 fps, another 16 ms for worst case vsync miss and 10 ms for the display latency makes it 48 ms. Majora’ mask at 20 fps would have 50ms + 8ms = 58 ms of latency, assuming it too doesn’t miss vsync