Programming.Dev is going to be going down starting at around 00:01 UTC Monday Dec 2 to attempt to fix the database corruption that happened relating to communities.
This has been affecting attempting to look at the pages for certain communities (it would end up loading forever instead of actually showing the posts for the community) and was affecting federation in some cases.
This is the second attempt to fix the issues with the first one needing to be rollbacked from due to the fix not working.
This fix could take several hours, so the outage window is going to be from 00:01 - 06:00 Dec 2.
Edit: Definitely not relevant, it was a problem with the link I clicked
original
Not sure if it’s related but I’ve noticed a couple of smaller communities from other instances which aren’t accessible from programming.dev any more, Imaginary Witches and Imaginary Fairies. They give the very helpful error “unknown”, this might be a fun one to try to track down. They’re accessible on the source sites (1, 2) and other communities from those instances seem to work.