source: Statistisches Bundesamt Deutschland (link considered malicous and can't be shared)

It states: 'For goods of German origin (e.g. re-imports), “DE” must be indicated.'

In DFO, when the country/region of origin is not known the country/region from the supplier is considered in the xml file. This is correct.

The same logic applies when country/region of origin is DEU and the supplier's country differs. In the .xml output file the expected outcome would be that the countryoforigin is DE for that item.