OK, so super weird. Private window behavior was the same. However, when I created a new profile (I am on Firefox 128.0), everything showed up normally. I tried everything to pinpoint the issue.

I restarted my faulty profile window with all extensions disabled, no change. I cleared all my history and cache, no change. I have a custom userChrome.css, so I moved it out of the way, no change. I logged out (because my new profile was not logged in), no change.

At this point, I noticed that the settings in my new profile window were different (I have "top 6 hours" selected in my usual profile), so I set everything to be the same as the settings in the new profile window. When I did that, everything started appearing again.

But the weird part is: when I reset it back to the way it was... everything is still working.

So I tried my best to get an actual answer to what's going on here, but I've come up empty. Something about resetting the settings frees up whatever was going on, in case anybody watching sees this.

Edit: so yeah, I went to my other computer, a Mac laptop - that was experiencing the same issue, and as soon as I changed "top 6 hour" to "hot" - everything came back. Subsequently changing it back to "top 6 hour" did not have any negative effect. So that's the "solution," such as it is.