Yes, we are aware of it. I possibly should have said something in the big post (though it was getting a bit weighty already!).
Lets call this comment my first techpost :)
Basically, the image storage may be slightly un-optimised, and we were running low on space.
When the upgrade happened, the space available became completely full, and the upgrade kept failing.
Tom tarred up some of the images, and put them in a storage location to give the install breathing room.
Because Emperor and I are planning to migrate anyway, the aim is to restore this once the migration is complete (no sense complicating things).
For a more technical answer, the image serving system splits the image files up into multiple folders.
I believe the smallest top-level one was removed (least impact).
Once the site is migrated, we're going to have a much larger space, and fingers crossed, I'll get things restored.
And yes, it's really bloody annoying to me too. I've lost my avatar!
The missing icons return "No such file or directory (os error 2)". It seems like different versions of some images are present. E.g.: The UK Memes webp thumbnail is missing but the png version is ok.
I think the feddit.uk server ran out of space and some of the pictrs storage was sacrificed to get the instance back online again. I don't know if they can be restored or regenerated somehow. Hopefully the new admins have some time to figure out and fix the issue. Otherwise I guess the community mods can just re-upload the images?
Huh, seems my avatar icon is affected also. If I try to re-set it to the same file, even after changing it to something else, nothing happens. I guess pictrs thinks it has that image already, based on its hash.