It seems to move exactly parallel to the camera, never twists around its own axis which you’d expect if it was moving diagonally away or toward the camera. Is it coincidental that it’s exactly parallel (if a distant object)?
If it was balloons or plastic garbage, the “legs” at the very least would move, changing the silhouette.
But if it’s something like dirt hanging near the camera, barely moving, or sandwiched between two plates of glass in the equipment ... Read even more