This BS started after the move to ZFS. The temporary solution appears to be: https://askubuntu.com/questions/1293685/out-of-space-on-boot-zpool-and-cant-run-updates-anymore/1374204#1374204

And then this to disable automatic snapshots in the future: https://askubuntu.com/questions/1233049/disable-automatic-zsys-snapshots-zfs-on-root/1279593#1279593
``
sudo mv /etc/apt/apt.conf.d/90_zsys_system_autosnapshot /etc/apt/apt.conf.d/90_zsys_system_autosnapshot.disabled
``

God, this is so annoying:
* https://askubuntu.com/questions/1382986/zfs-bpool-is-almost-full-how-can-i-free-up-space-so-i-can-keep-updating-my-syst
* https://askubuntu.com/questions/1233049/disable-automatic-zsys-snapshots-zfs-on-root
* https://askubuntu.com/questions/1246232/ubuntu-20-04-thinks-its-out-of-free-space-but-it-isnt


 couldn't save system state: Minimum free space to take a snapshot and preserve ZFS performance is