spoiler
Was Luthen in the imperial military or was he in a separatist militia in that flashback? I couldn’t tell.
Honestly one thing I found a bit interesting in Andor is it seemed to cast the CIS in a more positive light. Andor was in a pro-CIS insurgency, there are pro-separatist characters, even though they join up with the Rebellion which seems dominated by people who want to restore the Republic.
Luthen was in the imperial military, one of the soyldiers who he lied to about the radio thingy not working as a reason for him staying in the ship was wearing imperial army goggles around his neck