From given file I can see two things ...
- 80 MB file contains 20 MB of Orphan Data (materials and images)
- and than a weird thing ...under Outliner > Blend File there are four objects with materials that take the rest of MB.
To clean the file from those right click on each object (Cube.0011 ... .0014) and choose Delete. Those data (objects and materials) are still kept in blender under Outliner > Orphan data, Blender keeps it for next file opening (as some kind of backup). Open save it twice because first open-save delete material orphan data second delete images of these materials.
Why are mentioned objects kept in file I can't say, they are not linked, they are not marked as Faked User ... I don't see any relationship for those Data Blocks (that you can study closer in Outliner too) to behave like that.
- If there will still persist some images go to File > External Data > Unpack.
This was about how to store them in the blend, but you were speaking about appending into a new file ... How does that happened for you?
When I try to Append like Cube.0011 into a new file it seams to be fine. The only one weird thing here is light blue color of origin the appended object ... should be orange as outline. Light blue color is referring to Linked object (that is not) ...