I noticed that when I lived there in the very early 70s...they were just getting to the height of importation of Turkish Guest Workers. I could tell one day that would bite them in the ass.
I believe West Germany imported Turk while East Germany imported Vietnamese; when re-unification came about many Vietnamese were paid to leave. Turks don’t get citizenship, but they have a small advantage over others in that they use the German alphabet (with umlauts and such) since their modernization in the 1920s (prior to that they used an Arabic-type alphabet).
Now other “Euro-citizens” probably have preference over Turks (as non-Euro members); the Spanish government has publicly suggested that Spaniards that meet the qualifications emigrate to Germany and send back remittances (like Mexicans). The requirements are fluency in German and a skill.