I would argue that B-21 shouldn't be reduced to a role that's defined primarily around flying into an area and dumping explosive payloads in a kinematic profile that emphasizes endurance and range, and J-36 shouldn't be reduced to a role that's defined primarily around a kinematic profile that emphasizes maneuvering to attain a tactical employment solutions.
Both are "combat aircraft" with different kinematic profiles, but in context of the other traits that are shared between them -- networking, sensors, weapons, processing, system of systems -- those differences in kinematic profiles are rather marginal.
But as I said, continued use of the terms like "fighter" and "bomber" is natural and understandable, I don't really have an issue with that -- it's only the connotations that it evokes to the general public and milspace adjacent folks who will end up misinterpreting these aircraft based off their preconceptions of what those terms mean.
I would argue that based on very overt design commitments we can observe the J-36 absolutely features intended roles that prominently emphasize maneuvering to attain a tactical solution in its kinematic profile. The kinds of maneuvering can be different from earlier generations and still be very much about maneuvering advantage.
Keep in mind as well that going forth every new combat aircraft design is going to be very networked very EW very AI very system so simply using those characteristics as the anchors for tactical typology and classification isn’t going to be very helpful. Features you’re identifying as deserving of special emphasis are going to be the generic baseline going forth.