This photo from The Unknown Brewing Company made a bit of buzz as it's got a "triangle" UFO, as well as a weird shape made from lights.
But it's just lens reflection, mirrored about the center. You can see this by copying the lights at the top, rotating them 180 degrees, and then overlaying them on the bottom half of the image. I use a "subtract" blend mode, which makes the bright light look dark, and you can see they match exactly with the lights around the building.
Image source: https://www.facebook.com/unknownbrewing/photos/a.616898328359528/1942065045842843/?type=3&permPage=1