Was flying around our very wooded neighborhood this week with a P3-4K. When I looked at the video afterwards I ran across some footage with what appears to be six or so rectangles flying in a loose formation. I've attached a clip of the relevant footage (it's about 100mb). The motion and formation certainly indicates birds but their shapes are anything but birdlike. Perhaps they are birds distorted by an artifact of the rolling shutter? The rectangular appearance of these objects was even more pronounced in the original, 4K resolution video.