I have a web app which uses the DarkGray, DarkGrayLabels, ImageryClarity and ImageryLabels basemaps, using Esri.Leaflet. For unknown reasons, within the past 24 hours, all but ImageryClarity have stopped working, and I'm getting 403 errors for every tile that Leaflet tries to load. For example:
602:1 GET https://server.arcgisonline.com/ArcGIS/rest/services/Reference/World_Boundaries_and_Places/MapServer... 403 (Forbidden)
If I try to load that tile in a plain browser window, I get a similar "Access Denied" error. All the tiles for ImageryClarity, however (e.g. http://wayback.maptiles.arcgis.com/arcgis/rest/services/world_imagery/mapserver/tile/6036/14/4764/95...) still load just fine.
Any idea what may be going wrong?