The above commenter is wrong about it being capitalist, but they’re right about there being a ruling class in the USSR. The ruling class was the communist party, the “intelligentsia.”
The Bolsheviks and the Communist Party were not the Intelligentsia. The Intelligentsia predated the USSR, and was a cultural term for engineers, mental leaders, and other “educated” classes. The Communist Party of the Soviet Union was made up of various members, not exclusively Intelligentsia. In fact, the close-link to the bourgeoisie that pre-Revolution Intelligentsia had caused distrust towards the Intelligentsia.
Communist party members pre-selected candidates for all political appointments, and becoming a member of the communist party involved passing through multiple stages of party-administered education and then having your past scrutinized and approved by committees of existing communist party members.
This does not make the CPSU a class, nor does iy mean it was not democratic. The US functions in much the same way, outside of fringe areas where third parties win.
At its’ highest level of membership it never surpassed roughly 3% of the population. That is a politically privileged class that enjoyed better wages, benefits, general living conditions, and political influence than the general population.
Yes, Marxism has never stated that people cannot have it better or worse. Anarchists seek full-horizontalism, while Marxists seek Central Planning.
Even at the peak of disparity in the USSR, the top wages were far, far closer than under the Tsars or under the current Russian Federation, and the Workers enjoyed higher democratic participation with more generous social safety nets, like totally free healthcare and education.
The USSR was by no means perfect, but it was absolutely progressive for its time, and would even be considered progressive today, despite the issues they faced internally and externally.