I was suggesting (without knowing the pedigree of the various releases) it could’ve been on the actual cels.

Notice that particular marks, in any single frame, show up all over the green dress only (and not the wings, for example). Many times you can see it as if painted up to the color border, as a painter would do. A scan anomaly would violate all those constraints.

If true, then any later release sourced from film would have those marks, too, unless a “restoration” corrected them.