The posts that had broken images when I initially posted seemed to resolve themselves later that day. So yay! Those are working now, however …
A post I made today was edited by user system to “downloaded local copies of images” from the links a minute or three after I posted. This edit by system broke those images. Two of them were auto-generated thumbs for GitHub OneBoxes. The third was a celebratory GIF. Without the celebratory GIF, my post is just a sad panda.
I’d post an image of a sad panda to illustrate that, but that would probably break too, then I’d be a sad panda about a sad panda about a broken GIF. And nobody wants that.