Created attachment 223096 [details]
blender on FreeBSD without volumetric
Blender 2.91.0_1 from binary pkg and 2.91.0_3 from ports can't render volumetric in Cycles.
Volumetric work with Eevee only actually.
blender-ok.jpeg screenshot was taken from Obarun (ArchLinux without systemd). Volumetric work.
blender-novolum.jpeg was taken from FreeBSD. Same result with 2.91.0_1 and 2.91.0_3.
blender-novolum.blend is a simple blender file with a cube and volumetric shader "principled volume". This same file was used on linux and FreeBSD.
There's no error in terminal.
Created attachment 223097 [details]
Volumetric work on linux
Created attachment 223098 [details]
test file for blender