That's exactly right
It always 'looks' like a ball has changed its spin after it has been obscured by a post. It's because it disappears for a couple of frames so the continuity of its spin is broken up.
That's true. The other complicating factor is that the camera is panning up, and slightly across. The camera moves ever so slightly during the frames where the ball is obscured.
So the brain has to process the movement of the ball, the movement of the frame of reference, and the obscuring of the ball by the post.
This isn't a DRS or Hawkeye system based on fixed cameras.