UFO over California

I filmed this in December of 2019 when Corona was first spreading. I know because I got deathly sick from this plane ride and spread it to everyone. The girl behind me was coughing the entire time. I tried to cover my face and look outside, then I saw this. It started out as a dark, swirling object. I grabbed my camera immediately and started filming. It was huge. You can see that other jet fly by as well to give you some reference. Anyone have an idea what this is? #UFO #UAV #spaceforce #weatherballoon #