I don’t think its rpi or network switch, unless you’ve overclocked rpi with liquid nitrogen 😅. So, I assume its TrueNas device.
If it were a significant power difference, say 20-30 watts, you could easily find the process using htop/iotop. However, 6 watt difference is a relatively small value for a device with ~25 watts of idle power . It might be a process using just 1% system resources. That’s why I would look for systemd timers, cronjobs etc. to find scheduled tasks on specific times. Another possibility is automated S.M.A.R.T. self-tests. Those tests don’t show up in htop or iotop.
The worst part is, international laws and conventions are basically means nothing at this point. US actions simply incentivizes more countries to get mass-destruction weapons.
Thanks to these maniacs, Kim Jong Un now seems to be wisest person on the earth…