I think what we're seeing is the liberal sentiment about decolonial movements that was always there emerging. A lot of decolonial movements were supported either by socialists broadly, or by China and the Soviet Union directly. They've always thought that this was a cold war tactic of removing western territorial holdings, but did not say it in recent years. By bringing in the collapse or the soviet union into the same framework, they can essentially say it without ever having to explicitly ignore the humanity and agency of peoples in former western colonies.

Every liberal I've interacted with who believes in imperialism as a concept believes imperialism/colonialism is when Governments Do Things in other countries than their own

nah we passed that point centuries ago
words never meant anything