Yup - does not seem to affect Edge/Chromium on Windows, or Firefox on Android. I checked another Discourse based forum, and had the same issue there with the dark theme. It could certainly be isolated to one of my extensions. If I open a Private Window (no extensions), I don’t have the issue. I know the Facebook container extension blocks some things on this site that come from one of Facebook’s domains. Not sure what else could be the cause of it.
EDIT: CONFIRMED - this is due to the Facebook container extension (which I’m not willing to part with!) For some strange reason this theme must now be relying on a Facebook component of some sort Facebook container is causing various sites to misbehave. Ugh this extension must’ve had a buggy release.
It ensures that any assets a web site requests that comes from any Facebook-owned domains are blocked. It wasn’t showing anything blocked today, though I thought it may have in the past. Things like embedded Instagram posts would likely fall into this category.