One would have thought the "Ausländer' bias would have gone away after Merkel's long time in office.

No. Merkel left the borders wide open for years, supported by the left saying how positive this would be for social fabric, and by many conservatives and JCs wanting a bigger cheap labour pool.

The proles were told ‚together we‘ll manage‘ (‚wir schaffen das!‘) and ‚we‘ll all benefit from Syrian doctors‘ (who miraculously didn’t arrive, instead many with low eduction made it) while supporting investments were made hesitantly, if at all.

Like in most European countries there is lasting resentment about policies enacted despite a lack of buy-in by the populace - a good part of right extreme parties rising, as well as the Brexit vote, can be attributed.

That said, not that many immigrants would actually voluntarily live in former Eastern Germany.

The unconvincing reform policies by the federal government under Merz did the rest.