I just registered here to say thanks to @bAL, your solution works on my Odroid HC4.
I was bashing my head against the wall because I couldn't find what was constantly changing the fan PWM value even after disabling the fancontrol service. Now I finally have full control over the fan PWM (and thus the noise levels).
Thanks again!
So yeah, this issue is still relevant in 2025. `lsb_release -a` output for the interested:
Distributor ID: Debian
Description: Armbian 25.11.2 trixie
Release: 13
Codename: trixie
