This happens to my video renders from time to time and I have to rerender the video for it to go away.
This happens maybe once every third render. Sometimes I even get a different camera angle blended in. And the angle isn't even close to my main/secondary camera.
But for this one I'm working on now, I can't seem to get rid of it.
I can't find anything on google.
This seems to be a pretty specific "artifact".
Edit: I'm talking about the ghost-jizz on the right side.