Could you take a picture of what your describing? The custom cubemaps have a blurred look to them, not a perfect mirror. I did this because it was easier to make and edit them rapidly, second to try to make chrome blend into the environment with brighter ground color and sky. The vanilla was very dark in comparison. There's a few adjustments I'd still like to make but I'm saving that for a later update
For example this truck which has a chrome tank, with relight it looks matte (upper part). Tried it with two different trucks on different maps but get the same result. I think on modded vehicles that use Chrome relight might look a little brighter, besides that the matte look is intentional as I'm using it less as a reflection and more as a ambient light. Still looks good on vanilla vehicles since I tested it heavily on the chrome mac truck. I'll be tweaking it in the future but the matte look is staying