A Mishap in Measurement
This is pretty disappointing because it looks like a mistake that could have been easily avoided if this person installed had installed the door first and the vent second. But because of their poor placement and lack of measurement, the vent got completely in the way of the entrance of the room.
If they had installed the door first, they would have known they move the vent over a few feet, or they could have just made the door shorter. Although that may have caused a tall homeowner to have to crouch to get inside the room. Due to poor DIY skills, we have an awkwardly cut door.