Ask HN: Is MapQuest under attack?

The MapQuest open API (OSM nomatim Geo-coding etc) has been offline for a few days now.

Queries like https://open.mapquestapi.com/nominatim/v1/search?addressdetails=1&format=json&q=Berlin return "Nominatim is currently undergoing maintenance. We apologize for the inconvenience." and their forum is spammed by bots.

Has anyone got more information?