I suspect this isn't Orphix venom specific, but its the only point of reference I have.
Host migration removes the effect of all weapon mods for Archgun on your nechromech.
TYPE: In-Game
DESCRIPTION: After a host migration, arch guns equipped by nechromechs do base damage, acting as though no mods are equipped on them. I suspect if you have multiple version of the same archgun, like how everyone ended up with 4 mausolons that after the migration happens the game is taking values from the wrong gun (that isn't equiped by any loadout anywhere).
REPRODUCTION:
Kill s