Why SVG export looks so bizarre to me?

[KarlLegion]

1. For vectors only files, from the Export Settings, changing the "Use DPI" doesn't embed DPI property in the SVG (always 72DPI). Instead, the subsequent file has pixel size changed directly proportional to the DPI changed. 
2. For files with images, increasing the DPI has the same effect as the files having vectors only. However when you decrease the DPI, the subsequent SVG file will have BOTH the DPI and pixel size increased. (e.g. 1920*1080px@72DPI > Use DPI: 30 > export SVG > 2133.333333*1200px@192DPI) DPI is embedded in the SVG  when opened with Affinity. But when I opened it in Inkscape, it was reported has 800*450px which is directly proportional to the DPI decrease.
3. If you transform an image to make it smaller, then the exported SVG will have the same effect as what mentioned in point 2 above when decreasing the DPI. However, if you make the image larger instead, the exported SVG file will have no size and DPI changes.
4. Anything mentioned above will have the SVG file having objects sizes and position shifted. (<--no way to work pixel perfectly)
5. Exported SVG files will have some objects grouped under "Layer" while some not. So inconsistent. (<--what's the purpose of such structure? Seem to be unnecessary...)
6. Exported SVG has bitmap objects added 1 pixel width of transparent pixel around the edges (<--so bothering when align images in SVG)

It's so confusing and the export outcome is unpredictable and seemingly unnecessary.😕 Can anyone explain point 1,2,3 to me? Why Affinity make SVGs like that?

Related bug 4,5,6 mentioned:

 

[DWright]

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