Do you mean blatantly obvious at the time and from outside? Could you please elaborate? I thought the USSR put up a good front, and fooled much of the West with regard to economic development (not freedom).
Hollywood put out several productions that proclaimed the USSR was a paradise. [1][2]
US and European industrialists had gone over to the USSR pre-WW2 and helped them build out their industrial base. The Soviets had entirely failed at industrializing on their own. From those experiences, and people writing about them, it was fairly well known what general condition the USSR was actually in economically. Firm, reliable metrics however were largely unavailable throughout the Soviet era.
The fooling of the West, regarding the Soviet's mighty materialism output, mostly fell apart by the 1960s (the facade lasted for ~30 years or so, and mostly only for people that were sympathetic to that ideology).
[1] https://en.wikipedia.org/wiki/The_North_Star_(1943_film)
It's only blatantly obvious in hindsight. My vague memory of the history of it: There were many in the West who supported the Soviets as the future of humanity (not nearly a majority, but a not just a couple of wackos either - especially at the beginning). In the 1970s / early 1980s there was a major debate in the U.S. over whether to compete with the Soviets or just accept their power. U.S. intelligence thought the Soviet economy was doing well right up until the end.
Few people expected the Communist political system to collapse the way it did, but the lowercase-communist economic system was pretty obviously on its last legs by then. And indeed, look at what's happened: Russia abandoned lowercase-communism along with uppercase-Communism but certain features of the Communist political system managed to reassert themselves, in the form of the former KGB man Putin seizing and consolidating power. By this point, Russia's sphere of influence had retracted from eastern Germany all the way back to struggling to maintain control over Ukraine, but a little bit of brute force managed to keep Ukraine in line, too.
China, unlike Russia, managed to reform away from lowercase-communism while still maintaining the uppercase-Communist political structure. They are also just now attempting Great Power-style diplomacy over their neighbors, whereas Russia was overextended into that role ever since the end of WWII.
Sounds like we're edging into an old Cold War ideological fight, attributing things to characterizations rather than addressing the ideas.
How does the parent post explain the CIA and Henry Kissinger's 'Detente'?
EDIT: minor edit, more edit
Detente was a short-lived policy of the Nixon years. By the early 1980’s, US foreign policy pivoted more strongly to a consistent anti-Soviet stance, consistent with the neoliberal revolution in economics that predicted the failure of central economic planning and invalidated countless Nixon-era policies both on the domestic and foreign levels. It may have been a surprise to the West just how much of a house of cards the Soviet bloc was, but it was probably also a surprise to Gorbechev that the Soviet system couldn’t survive his attempts at reform.
The far more optimistic notions about the USSR had their heyday during WWII, when their rapid industrialization and valiant defense against Hitler won them considerable respect, and the “enemy of my enemy” situation shielded them from the now-obvious criticisms of Stalinism.