There is a rectangular area which is an exclave of the commune of Ferrera, which borders a single Italian commune and the commune of Avers. Everything looks correct in the database, the country border on 3 sides and communal border on the 4th side renders correctly. However there is a rendering of an hypothetical 2nd communal border which lies in diagonal within the rectangle. This border is not here in the database, and the area was not changed recently so this is not leftovers from a previous rendering of the map. So I think the rendering of this border is due to a glitch. I could be wrong.
Interesting. It does seem to run from one node to another. It maybe an artefact after a change or an error in the planet files used for rendering or a rendering bug.
I’ve removed and recreated the lower node. Let’s see if that does something.
“Tickled” the boundaries of Avers & Ferrera by sorting the relations (will change relations in osm database) and moved all nodes of https://www.openstreetmap.org/way/122998656 just a very little bit (this will update involved way & nodes).