I get that people tend to instinctively side with the USSR because it's the socialist state they learn more about etc, but, like, the sinosoviet split is unambiguously on the USSR's lap - the CPC was fine to politely advocate marxism-leninism and oppose revisionism in hope the CPSU would reverse course, until the (consistently paternal) USSR got scared by the prospect of a nuclear-armed China it couldn't control and punitively withdrew all technical aid. Even earlier, the USSR had supported the KMT over the CPC in the civil war, in an effort to keep Russian Imperial territorial claims recognised; and had backed the DPRK in war against the ROK with the hope it would draw China into the cold war and grant it Russia's old naval bases in China. The idea that national interests only emerged between socialist powers due to the split, or worse, due to China, is exactly the mistaken attitude that underlied Soviet paternalism. Even the most egregious episodes of the split, such as support for the Khmer Rouge, can be understood through the lens of national policy (rather than as instances of sudden insanity in the communist party) - the Socialist Republic of Vietnam, having sided with the USSR against China and forming another border the PRC had to defend, made very clear its territorial ambitions to annex Cambodia as part of a 'socialist indochina'. The support for nationalist (not communist!) groups in Cambodia was spurred on precisely by the USSR's ally, and by the USSR's 'internationalist' view that revolution could be forced on another nation by military occupation. The USSR was revisionist, yes, but moreso it was of the position that its interests were the interests of all proletarians, when that was simply not the case. Soviet national interests, and the Soviet denial of the existence of its national interests, were the immediate cause for the split, which, to a certain degree was the inevitable flailing of a state which found itself existentially doomed after the invention of the cold war.
