I've posted about this before (with comparison pictures), but Caudabe seems to be changing the slick back of the Paragon.
The black 17 Pro Paragon Precise I've had since launch is really slick, but the black Paragon I've got for my S26 Ultra is much more textured on the back, making it less slick.
I recently got the Moonstone open Paragon for my 17 Pro, and while it's not as textured as the S26 model, it's more textured than the black precise and thus less slick.
I think the 18 Pro models will be much more like the S26 model where the back isn't nearly as slick.