I just moved "name=Referenzfläche" from the outer way to the relation, for background see fixing https://github.com/osmlab/fixing-polygons-in-osm/issues/15

The original way is deleted but you can still find it: https://www.openstreetmap.org/way/291483543/history

Versie #1- atpl_pilot

13505 / 13507 Berlin-Nord: Landuse für Friedhof, Residential, Forest und Naturreservat den Verlauf korrigier- PLZ Grenzent admin_level 8 hinzugefügt 

Introduced via https://www.openstreetmap.org/changeset/23969398

Please contact @atpl_pilot, I see that account is quite active and might know more.