When the subject moves in and out of the edge of the image, it creates quite a lot of artifacts.

Is there a solution to these? I do improve on the way I manually write the subject, But when there are a lot of frames to work on, it takes a lot of effort on my part.

I'm sorry if you can't understand. My native language is not English and I have poor English skills.

You can add a border to each frame, or there is some users who add a black border in all edges. Other than that I don't know any other solutions.