1918 Austria Overprint Query

Hello,
I am hoping someone may be able to shed a little light on this mystery (at least to me) stamp. Shown is a 20heller Austria Sc 169 overprinted with block Deutsche Oesterreich. The stamp is on a complete cover mailed 21.11.18 to a local address in Schwertberg (town to the east of Linz). I assuming this is a local overprint from the time of the formation of the Austrian Republic in 1918. Scott doesn't show this overprint; the online Austrian Philatelic Society paper on 1918 shows no similar overprint in their article. Perhaps in Netto, Michel, or Sassone?
Thank you to all,
Thomas

Never seen that overprint ,interested to learn more about it . Looks like a modern creation would be my first guess . Because the cancel and overprint are different .