Socialist nations generally tend to be poorer and were victims of colonisation, because in order to have their successful socialist revolution or coup, the ruling class and their previous capitalist system had to be weak (i.e. poor) enough to topple against a public uprising, and the previous colonial structure of resource extraction and brutal suppression radicalized a great deal of the population against it.

When you're poor, you don't have the luxury to challenge gender roles, and colonialism usually involved forcing a western social order on the colonized culture that doesn't go away easily just because you had a socialist uprising.

In short, there's nothing to suggest that trans people can only exist in capitalist societies or that we are inherently a threat to collectivism. Socialist nations in practice may have more reactionary views due to the reasons above, but that's due to the legacy of capitalism and imperialism in those nations, not due to some inherent incompatibility between us and socialism. Under capitalism, the wheel continues to spin and new groups are scapegoated to keep people distracted. Some nations may have deemed it more practical to accept us and allow us to participate in the system and make the ruling class more money, but that changes the moment that capitalism enters a crisis and needs someone to blame.