Mirror view skewed on HP Reverb G2

[Entretoize]

I'm building a game with unity and SteamVR, and the mirror view as a trapezium. I'm recently change my headset for a HP reverb G2 and it's thre first time I have that issue then I think it's related. I tried with a fresh project and it is the same as soon as I add SteamVR package, is there something I can search for to find a workaround ?

EDIT : I can get a working mirror by adding a second camera inside the camera rig and setting it to main camera on a highter depth