Apologies for the downtime of lemmy.kde.social. I made a minor update to our lemmy instance on Friday and this was a bad idea as this broke the server. I roll-backed our server from the last backup but ended up with the same issue. I unfortunately didn't had the time to investigate the issues during the weekend.
I finally got time to fix the issue and it turned out to be caused by a missing update of the upstream docker-compose file that I missed to apply on the server which caused an internal DNS issue between the frontend and backend.
Lesson learned, I won't do any update on a Friday anymore.