I updated an application I've been working on for a while, from API version 4.18 to 4.19. When I did that, my Search widget no longer worked (there was some sort of message above the widget about no results available). I was able to fix that by removing my developer apiKey from my code (that was the standard esriConfig.apiKey = ...), but that made unavailable some basemaps that I explicitly added to my BasemapGallery widget (via this code: source: [that.Basemap.fromId("topo-vector"), that.Basemap.fromId("arcgis-imagery"), that.Basemap.fromId('osm-streets')]). The latter 2 basemaps appeared dithered in the gallery and some errors appeared in the developer console.
Putting my apiKey in the Search widget instantiation didn't help the situation. For the time being, I don't have my apiKey in the code and am just letting all default basemaps appear in the gallery, and everything is working.
I'd say this is a minor issue given the effect it's had and the small compromise I've had to make (all basemaps instead of the few I want), but thought that I should bring it to light.