distro.version() is supposed to eliminate n/a and empty values when other sources contain valid values.
>>> import distro
>>> distro.version()
'n/a'
It returns n/a because lsb_release -a has that value, even though /etc/debian_version contains a valid value
$ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description: Debian GNU/Linux trixie/sid
Release: n/a
Codename: trixie
$ cat /etc/debian_version
trixie/sid