While it is generally true that USSR was one huge inefficient and badly managed corporation (not that different from any huge multinational corporation), which BTW eventually voluntarily downsized, the situation was very uneven and this corporation did produced several competitive high tech goods, especially in military sector and heavy machinery.
I think the key here was that they overextended themselves by huge overspending on military sector desperately trying to reach parity with the USA. It was the biggest strategic mistake they made and that was the main reason they destroyed the civil sector due to systemic underinvestment.
They also paid too much attention to heavy industry and underestimated the importance of consumer sector which was the sector people were the saying “We pretend to work, and they pretend to pay us.” BTW is not that true about any McJobs?
Science level, especially nuclear and materials science level was OK. Paradoxically the level of qualification and level of talent was pretty high. That became quite clear after mass emigration of their techies, especially programmers, to the West after the dissolution of the USSR.

You could probably throw in our foreign adventures and a propensity to want both guns and butter into the mix.

Shaken, not stirred.