Xbox Series X will have a new design regarding Xbox Store, currently being tested already on Xbox One with the code name Mercury, of which you can see some first screens and functions in this new video leaked online.
Project Mercury was initially planned as a general update of the Windows Store app on PC, but at this point the new version seems destined to be used also by Xbox Series X. The Mercury interface is currently being tested but the graphics adopted goes towards a greater convergence of styles and visualization between Xbox One, PC and Project xCloud Xbox Game Bar on PC, with rounded corners, a new organization of tiles and windows and a new font used for texts.
In general, the system is probably clearer with one navigation bar side and fewer elements to crowd the screen, making navigation on the system more pleasant. Although this is probably the interface that will be adopted by Xbox Series X, it will be introduced already with Xbox One probably, as Microsoft’s intention to keep the interface design of the Xbox Series X at launch very similar to the current Xbox One is already known, in order to keep the experience continuity from one to the other.