You mentioned that you don’t see the problem on osm.org, which means the issue is probably fixed in the database. That doesn’t mean it will immediately be fixed in renderers.
I don’t know if this is related, but that site may not be using the recommended tile URL as set out in Tile Usage Policy. I see a lot of references to a.tile.openstreetmap.org (and b. and c.) here, which I don’t think is up to date:
Technicalities aside, note that verkehrslage.de has chosen to use the free tiles provided by OSM which offer no guarantees.