Why the preview isn't always exactly the render

The editor's canvas is fast because it isn't Manim. It's a quick stand-in that redraws instantly while you drag things around, so you can compose and time a scene without waiting. The render is the real thing — the actual frames that ship.

Two different tools doing two different jobs. The gap between them is small in most everyday work, but it isn't zero. This page is an honest map of exactly where it is, so a difference between what you edited and what came out doesn't look like a bug when it's expected.