Question [URP] Camera overlay - no PP

Hey,

Using URP 2021 LTS.
I have 2 following cameras (Orthographic):

One Default Main Camera with

• PostProcessing : true
• Volume Mask = Culling Mask = Layer = Default

One UI Overlay Camera, in the stack of the Main Camera.

• PP : false
• Volume Mask = Culling Mask = Layer = UI

My problem is that my UI layer gameobjects are affected by PP. (Canvas is set to Camera)
Even worse, the PP effects is more effective on the Default Layer GameObjects, while the UI Overlay camera is active which should be impossible since the Culling & Volume Masks are disjoint.

What am I doing wrong ?
Is the "PP" option on the Camera overlay working ?

Regards.

Edit: I found out that only WhiteBalance of the Volume is having this behavior.