A few days ago, Openstreepmap obviously made some changes with their tile servers. They seem to block requests now, when the requests come from Electron applications. This is the case in most MagicMirror installations. As a consequence, MMM-RAIN-MAP does not show map tiles anymore.
I suspect, that also other modules are effected.
One possible fix is using another tile server for MMM-RAIN-MAP. One that still works at the moment, is the German fork “https://a.tile.openstreetmap.de/${z}/${x}/${y}.png”.
I will adjust the module soon, to use this tile server as a default.
You can also change the tile server by setting this property in the module config:
{
mapUrl: "https://a.tile.openstreetmap.de/${z}/${x}/${y}.png"
}