A bit confusing as it somehow includes metro lines in China that are still in construction or even only planned, and it seem there is no way to filter them out.
If you can pinpoint the data in OpenStreetMap we could try to figure out if this is something wrong in the map data (Anyone can fix it!), or maybe it's a tag they should be filtering out on the OpenRailwayMap rendering.
Hmmm, the specific case I was looking at is the North extension of Nanchang Metro Line 1 to 昌北机场. Which doesn't exist yet.