I’m experiencing something similar. I’m not using the Disguise device but I am attaching the VFX Powerup directly to the player. The issue seems to occur only when switching between first- and third-person cameras.
In my case, when switching back to third-person from first-person, there’s some odd clipping at first (as shown in my video). After clearing and then reattaching the VFX Powerup, the Custom Effect Socket resets to Base. In my case, this only seems to be affecting the VFX Powerups set to Custom Effect Socket Head and Chest; another piece that’s set to Pelvis isn’t affected.