1. Create a course
2. Add a page
3. In the page content, upload an image which is about 2MB in size
4. Save the page
5. Create a course backup - Note the size of the backup created, should be about the same size as the uploaded image.
6. Go back and edit the page, delete the image from the editor and save.
7. Create a new course backup, you will see that the size of the backup created is exactly the same

Expected behaviour - backup should be less size without the image.

Additional step:

Delete the page entirely, take a backup and the size should be in kilobytes as the image has now been deleted.