tiles.wmflabs.org is part of the maps Cloud VPS project. It provides OSM tiles for WikiMiniAtlas (https://wma.wmflabs.org/) and other projects created and maintained by the Wikimedia technical community. The service it provides is awesome, but it runs in a Cloud VPS VM and uses an NFS share as its rendered tile cache. These things make me a bit nervous about the potential for the service to go down and cause interruptions for the on-wiki users.
@MaxSem knows a bit about WikiMiniAtlas's use cases, but it would be good to track down and talk to the actual folks who are keeping the current tools alive to find out what the major use cases are and if they are compatible with Kartotherian.