It stopped being a particularly meaningful term when the distinction between "middle class" (bourgeoisie) and "upper class" (aristocracy) stopped being meaningful. After that it's just been used to make some variation of "those more privileged workers who get tasty good boy treats as a reward for being white landowners in the imperial core" feel special and separate from other workers.

There's definitely an analysis to be made about how the intersection of privilege, land ownership, and petty capital ownership creates a reactionary class of precarious but entitled shitbags who are simultaneously murderously terrified of losing their meager fiefs and rewarded enough by the system that they support it against any and all change, but "middle class" is too empty and propagandistic a term now.