This video from MUFON shows a white object shadowing a jet. The person who made the video says that other jets and helicopters followed soon after. There is nothing to suggest that this object is a drone, a balloon, a bird or any natural object. It is also pacing the jet, so it’s not a celestial object. The only possibility other than a UFO is that it is a smaller plane at a lower altitude and so not emitting a contrail. But it is moving very quickly.
Your Out There editor concludes that this has a better than average chance of being a genuine unknown.