Gunned for a random Vanguard today and when switching to first person view I look from inside of the Mjolnir model, see screenshot. Switching to third person view - all normal, switching to FPV - again from inside. Exiting/entering dis not help. Nothing game breaking tho.
It's happening on the harasser one too. See here: https://forums.daybreakgames.com/ps2/index.php?threads/mjolnir-h-visual-bug.253562/
Fixed. April 15, 2020 - Tactical Improvements (PC Update): M96 Mjolnir (NC Top Gun) first person camera fixed for both the Vanguard and Harasser.