Windows Search down for many
TL;DR: The issue is reportedly related to Bing, and the “fix” being suggested involves using RegEdit to disable Bing integration. Not for the faint of heart!
It's also pretty inexcusable . . .
https://kevin.thecorams.net/posts/2020/02/windows-search-down/
I still think it is pretty inexcusable. A core bit of OS functionality should not be at the mercy of whether or not some backend service is up and running. The online piece(s) of it might go down, but the local search functionality should still work! There is no excuse for the whole search window to render as nothing more than a solid black rectangle.