~~If I enter it manually on the website in my browser as /c/!zelda@lemmy.ml, then it comes up with the error page in the screenshot in my comment. I could be doing it wrong, though.~~

I was doing it wrong. I didn't need the !. When I got it to work, I was able to re-subscribe. I don't know how I got usubscribed over night without me doing anything, though.

The "Connect for Lemmy" app apparently caches my subscription list, and if I click it there, I get shown posts from "Humanities". See the attached screenshot. (Not sure which instance that community is on.)

Lemmy.ml still federates with sh.itjust.works. I checked their list.

What's going on?