Apps instalations fail with “no space left on device”

Trying out Umbrel (proxmox virtualized 4 cpu core / 8 gb ram / 40 gb ssd machine) and at some point after 2 or 3 services, they stop installing.

Logs show:

Aug 18 12:36:23 umbrel umbreld[17581]:  e1030a9ee431 Download complete
Aug 18 12:36:23 umbrel dockerd[450]: time="2025-08-18T12:36:23.046669080Z" level=info msg="Attempting next endpoint for pull after error: failed to register layer: open /usr/share/perl5/Debconf/Template/Transient.pm: no space left on device"
Aug 18 12:36:23 umbrel umbreld[17581]: failed to register layer: open /usr/share/perl5/Debconf/Template/Transient.pm: no space left on device

While at the same time, there’s plenty of space:

$ sudo df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            3.9G     0  3.9G   0% /dev
tmpfs           794M  2.2M  792M   1% /run
/dev/sda2       9.4G  4.4G  4.6G  50% /
tmpfs           3.9G     0  3.9G   0% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
/dev/sda4        21G  7.3G   14G  36% /data
/dev/sda1       200M   49M  152M  25% /boot/efi
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/03975920ceced3a5e3588249c989b6f64baf733ca6972420b9ffef7726fd342e/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/b270097decc42bcdc2860bb6a7582295fe0428f1646dd3fd79c267a6893f05ca/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/588fe96d85f26597bc72fa0d5a17012fcd624410d0c9611596c297c059572546/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/44fe00649957a8dc4375c4bb317628d29251dcd07c69f7bbb5135353f4d5c601/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/8a0d03f72aedaa7134340ad62dbe51ce16b799c682a79f49838777fcfe88ca86/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/2135fcf5b5ebac037f26bb7e3357f25fe983a81510af42316cfc1e98b53bac2c/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/7db24a89c2db7a7c73d8a60ccc328e1aec611b87fb594dfaa9e68c13ebb67f67/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/302a5de6010687402f5cbb85928c992020759504237c42dcf003ce4ba875c500/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/8888e9b3a9e6c89d90ad1879c630e4a3b4a49907c36b43d3f4e7dc669363a50e/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/4ce549b9bd33076ad36a08fc0ffcd4be386c551b1748e46deef1d9d6ce85332b/merged
overlay          21G  7.3G   14G  36% /var/lib/docker/overlay2/0d523fdc5b88ed03e39d2525018ca07a0d1bfe8af5943ef738747ddd229cc833/merged
tmpfs           794M     0  794M   0% /run/user/1000

I would expect the reason is tiny tmpfs that installers are trying to use to unpack large packages, but surely I am not the only person trying to install plex, homeassistant and adguard on the same machine.