I wouldn't say it's "intended" behavior, but it is acceptable behavior. The player would never see the mask, so they wouldn't know anything is wrong. At most it would overlap by a pixel or two, and as long as it's not causing any shaking or jittering, it should be fine.
This essentially happens because we are using a larger app surface than our view, meaning that the difference between the coordinate positions of 4.0, 4.25, and 4.5 is actually visible. So the player's y value is something like 4.25 which wouldn't fire off a "collision" (as place_meeting uses rounded values only) but we can still render the difference between 4.0 and 4.25 on screen.