I had noticed that (dewp's) Geohack's preview OSM map has stopped working, and @Strainu reported the failure of the, eh, pop-up-able OSM map at the top of wiki articles [[https://de.wikipedia.org/wiki/Wikipedia_Diskussion:WikiProjekt_Georeferenzierung/Anwendungen/OpenStreetMap#The_tiles_do_not_show_anymore|as well]]. This is due to the #Tool-Labs project's tool "wiwosm" referring to `a.toolserver.org`, `b.toolserver.org` and `c.toolserver.org` which have stopped working as well. I'm not sure since when this does no longer work (cf. T85165).
I don't know what the difference between the three hosts was/is and why https://wikitech.wikimedia.org/wiki/Nova_Resource:Maps lists no instances for the Maps project while individual instance pages as for example https://wikitech.wikimedia.org/wiki/Nova_Resource:Maps-tiles2.maps.eqiad.wmflabs seem to exist, but as that OSM plug-in currently just shows a blank canvas, it should be fixed really soon. This could either be done by setting up the redirects (again?) or patching the "wiwosm" tool.