Linux: Maintenance tool ignores free space on NFS home

Using the online installer to install the Qt open source version, the installer complains about to less space in /. But installation target is a NFS based Home with enough free space.

Output from -v:

[31206] Tmp is on a different volume than the installation directory. Tmp volume mount point: "/tmp" Free space available: "9.17 GB" Install volume mount point: "/" Free space available: "1.37 GB"
[31206] Installation space required: "1.97 GB" Temporary space required: "771.43 MB" Local repository size: "0.00 Bytes"

Installation Target is my home on an NFS mount:

thw@hera:~$ df
Dateisystem 1K-Blöcke Benutzt Verfügbar Verw% Eingehängt auf
udev 16189932 0 16189932 0% /dev
tmpfs 3243076 1536 3241540 1% /run
/dev/mapper/vg_system-root 3030800 1420172 1436960 50% /
/dev/vg_system/usr 30832636 23966764 5276624 82% /usr
tmpfs 16215368 233848 15981520 2% /dev/shm
tmpfs 5120 4 5116 1% /run/lock
tmpfs 16215368 0 16215368 0% /sys/fs/cgroup
/dev/nvme0n1p1 201633 289 201344 1% /boot/efi
/dev/mapper/vg_system-data 114868800 93397004 15613700 86% /data
/dev/mapper/vg_system-var 10190136 1599764 8049700 17% /var
/dev/mapper/vg_system-tmp 10190136 27020 9622444 1% /tmp
/dev/mapper/vg_system-opt 15350768 331124 14216828 3% /opt
tmpfs 3243072 264 3242808 1% /run/user/1443
theta:/home-thw 314667008 196961280 102716416 66% /home/thw
tmpfs 3243072 0 3243072 0% /run/user/0