When scanning German ID cards from before 2021, the masking of the ID Card number (Ausweisnummer) on the silver strip on the backside is not correct, and it is still visible in the export then. The ID card number is further to the right on the silver strip of the pre 2021 ID cards.
There should be a drop down selection for backside scanning for pre 2021 ID cards, with an adjusted ID card number mask position (on the silver strip).