che auto upgrades failing
che had all packages pending upgrades, which is a quite unusual situation for any debian host, IMHO. I don't quite understand what happened there, but it seems like no upgrade had been running since buster was stable. To quote my backlog:
E: Repository 'http://deb.debian.org/debian buster InRelease' changed its 'Suite' value from 'stable' to 'oldoldstable'
and:
176 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
So anyway, I did that upgrade by hand, but che will need some special hand-holding, I think.