Your comment with trimming helped me with the imminent problem.
However, I wouldn’t have known about the trimming feature if I hadn’t stumbled over this feature request.
When recording a partial screen, I move the controls view out of the recorded area. When I record the same area again, the controls view could remember its position from last time and be outside the recorded area right from the start.
Currently the controls are always back inside the recorded area, which is annoying.