I found that search widgets don't show up sometimes even for simple queries like the name of a city (can be other stuff like "ChatGPT" for instance). To "force" them I found that switching between safe search on and off works, but I can't really say why.
First picture with safe search ON (first query).

Then, I turned safe search OFF, and the widget shows up.

But it happens in both ways, and I don't think it's safe search that's at play here, but maybe some sort of caching issue going on if that makes sense. Note that after some time, it will show up in the mode where it didn't. I suggest trying to reproduce with other queries if possible.
Another way to reproduce: for example if I search "kyoto", widget doesn't show up. But if search "Kyoto", then it shows. Very much looks like the first query didn't wait for the wikipedia widget.
I very much doubt this is a client issue, but just in case I'm using Brave Browser on macOS with no extensions. Also happens on mobile. No errors are reported in the console when the widget doesn't show up.
Connection is made from ASIA-EAST if that matters.
Thanks for looking into it!