I was curious about this case, so I ran the model through nEVEn.
The geometry and texture inventories were both empty, but the extension database scan told a different story.
It found 734 MB of data stored under PBR_TEXTURE_TOOL, which matches what @Elmtec-Adam identified.
After a cleanup and rescan, the model dropped from 566 MB to 0.1 MB.
It’s an interesting reminder that large SketchUp files aren’t always caused by geometry or textures, extension metadata can sometimes be the culprit.
