How to instantiate only a single material of a MeshRenderer?

Hello,

I have a GameObject with a MeshRenderer using N materials.
Now as soon as I change a property of only one of these materials, all others become instances as well.
It seems like as soon as you access MeshRenderer.materials, it will convert all materials to instances.
Is this intended behavior? What if I only want one material to become an instance?

There is a useful tool

Watch the video, how to