What’re your thoughts on the concept? From what I’ve read, what’s most commonly allegated as “colonialism” in the USSR is stuff like the dependency of Central Asia on goods from Moscow (sometimes spun as the “metropolis”) and systems inherited from the Tsarist government which were phased out during centralisation, so the foundation for such an argument seems shaky - especially considering the massive efforts to modernise the colonial territories that the Soviet government undertook. The closest thing I can really find is the deportation of the Crimean Tatars, which was definitely bad but was also a singular event brought upon by the second world war and not really indicative of a greater system of colonialism at play.
The Soviet Union did the exact opposite of colonialism. It exported wealth from the Russian core to the peripheral republics so much that a common complaint of anti-communist Russians today is that the Soviet leadership took from Russians and spent too much on affirmative action and development boosting programs for the various minorities and republics.
This is exactly what virtue signaling liberals who claim to give a shit about minorities and colonized people in the global south say they would like to do, but they end up somehow doing the opposite, supporting white supremacist neoliberal austerity policies that disproportionately harm minorities in their own countries while upholding colonialism and imperialism abroad.
It is yet another of a million and one instances of projection from Westerners. The Soviet Union was deeply and thoroughly anti-imperialist and anti-colonialist. Lenin explicitly built it to be that way, he recognized the old Russian Empire as a Prisonhouse of Nations and designed a system that would be its complete opposite by liberating and uplifting said nations.