post processing effect with multiple cameras - is it lie?

I’m building a 2d platformer game that will involve a lot of cave areas.
I’m trying to achieve the blinding effect for a few seconds when the player exits from the cave and of course the opposite effect when he returns back to the cave.
To do it I am using a collider that detects the player’s direction in/out and adjusts the weight of the relevant global volume.

I am using two cameras, a base camera for lighting sprites - outside the cave (layer urpLight) and an overlay camera for the cave sprites (layer urpDark).
base camera - layer urpLight - culling mask: urpLight - volume mask: urpLight
overlay camera - layer urpDark - culling mask: urpDark - volume mask: urpDark

the cave relevant sprites under urpDark layer.
outside sprites under urpLight layer.

I also have two global volumes
blindness (bloom) - layer urpLight
darkness (color adjustments, vignetee) - layer urpDark

When player go out of the cave, the blindness disappears (volume.weight 1 → 0 slowly) in parallel the cave needs to become darker (volume.weight 0 → 1 slowly).
the problem is that some how the overlay camera darkness affects the layers outside the cave (urpLight).
I can’t isolate the darkness global volume to a specific layer; it effects my other layers on the base camera.

can someone advise how to solve it? thanks.