cyberbits is official archive mirror but does not mirror archive
The official archive mirrors are currently these 3 (from https://f-droid.org/archive/index-v1.jar):
"mirrors": [ "https://ftp.fau.de/fdroid/archive", "https://mirror.cyberbits.eu/fdroid/archive", "https://fdroid.tetaneutral.net/fdroid/archive" ]
But cyberbits mirrors only the main repo.
See directory listing: https://mirror.cyberbits.eu/fdroid/
index-v1.jar returns 404: https://mirror.cyberbits.eu/fdroid/archive/index-v1.jar
I checked which repos mirror the archive: https://gitlab.com/marzzzello/mirror-monitor#repo-archive