Just for the sake of it I tried installing the latest Yunohost on Debian 12. Then tried to restore the conf backup from the old Yunohost on Debian 11 and I got this nasty error:
Could not load info for archive '/home/yunohost.backup/archives/auto_conf.tar'… The info.json file cannot be retrieved (or is not a valid json).
I wonder if this is related to his Borg Restore Backup file without info.json - #9 by NoCodeOnlyIssues
Or could it be that the .json files from YNH Deb11 are not compatible with those from YNH Deb12. Or is Borg broken…?!