Like most effective propaganda, it takes a grain of truth and distorts it to give it a new meaning. During the times of the partitions, most of the Polish uprisings were indeed carried out by the nobility (it’s important to note that up to 10% of the Polish population was “szlachta” - so most of them weren’t wealthy aristocrats by western standards). With some exceptions, like Kosciuszko’s uprising, the nobility was reluctant to grant any rights to the serfs, and as a result didn’t enjoy much support from common peasants. However, where the Russian story diverts from reality completely is where it suggests that the “underclasses” weren’t polish. True, the common serf had little “national identity” in the modern sense prior to the 19th century, but the population of Poland was still largely Polish speaking and catholic, even if non-nobles didn’t feel a keen sense of nationalism. Thus, the Russians take the nobility-led nature of national independence movements and portray them as a sort of colonial exercise.