Noise and quality issues with multimatte objects in render output

hello.
I’m using Sketchup 2024 and Vray 6.20.06.

I’ve been using MultiMatte Objects in render Elements for post retouching in Photoshop with good success,
For some reason, the RGB channel of the MultiMatte is noisy.
And when I select the red channel for example, the lines of other objects are selected along with it.
Here are the render settings for my work.

Here, the same thing happens even if I increase the Subdivs value or increase the Quality or Resolution. What could be the problem?


The output looks fine on the surface.


But if I try to select a channel in Photoshop,
things like noise or lines from other objects are selected.


Is anyone else experiencing the same symptoms as me?
I don’t know if it’s a setting value or a technical issue, but I’d like to fix it.

Thank you for reading this long post.