The abstracting concept of "protected group" is not commonly understood. I had never heard of it before this thread. Anti discrimination of course is, but not this specific term.

Neither in the German Wikipedia nor in the Duden (German dictionary) or on the website of the "Bundeszentrale für politische Bildung" (Federal Agency for Civic Education) can I find any reference to "geschützte Gruppe".

The German constitution, explicitly states: "No person shall be favoured or disfavoured because of sex, parentage, race, language, homeland and origin, faith or religious or political opinions. No person shall be disfavoured because of disability.".

This is often emphasized in things like job postings, but never in abbreviated/conceptualized form.