LibreOffice Writer saves background image in document, but does not remove it, after deletion or change, which can lead to massive document filesizes.

Steps to reproduce:
1. Format > Page > Area > Fill > Bitmap > Import Graphic (choose any .jpg or .png)
2. Apply, and notice the larger filesize (image has been saved in document)
3. Reset Page Fill to Blank or None
4. Notice the filesize does not reduce! The image remains inside the document.
5. Repeat steps, import new graphic

Result: Filesizes of 10+mb for a single page document can be the result, if users tries three different background images (just an example).