I've assigned the exact same material to the frame/legs object of this bench, as well as the slats objects running across. It's a "painted" texture using a color ramp and voronoi texture that I copied from a Youtube tutorial, which allows lights to affect the material but still give it a 'painted' look.
In the render preview, the slats look correct but the base is only displaying the brightest color in the color ramp. In the material preview, the base looks much brighter, and has some texture to it, while the slats look flat.
When I imported the bench object, it had different materials applied, so maybe there's something left over that's causing this? Flipping between the slat and base objects, I can't find any differences, though.