I have had a repeated issue with my epic hackslinger mod downgrading in slot. No indication of any condition triggering it, it just suddenly goes blue or green. It's not cosmetic; the stat changes as well.
From my experience it's either if you put your clothes in your stash, either after a BD.
But you can report it directly to the support if it's not already done ("Contact Us" button)
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Did wonder why it happened so sudden on all my equipped clothes at once as the only thing connected to the issue I had noticed was on stash transfers, didn't know BD's also triggers it.