That whole panel is foam, wouldn't be hard to cutout a square.It can't be a Mazda 3. The filler door on the 3 is round, on the mule it's square.
But yeah, regardless, it's a Subaru. The rear pic of the mule and the LGT I posted is proof, and honestly, kind of a dumb mistake on Subaru's part if they're trying to hide it so much.