From many Hexbear threads on the topic of LGBT rights in the Soviet Union (and Warsaw Pact countries), here’s my understanding:

• The pre-Soviet Russian Empire criminalized homosexuality.
• The first Soviet constitution “decriminalized” it in the sense that it wiped away the laws of the old Empire and instituted new ones that did not include criminalizing homosexuality. I don’t personally think (and I think this is the Hexbear consensus) that was an intentional choice; it probably just got left out because it wasn’t a priority in the midst of a revolution, civil war/invasion by a half dozen capitalist powers, and the monumental task of building a modern state (and the first socialist state) out of the ashes of WWI and late-feudal Russia. Note that plenty of legal scholars would disagree on the theory that legislative bodies write laws (or don’t) very deliberately.
• Stalin re-criminalized homosexuality. Zero people on Hexbear support that, and I’m not aware of any existing socialist state that does, either (the CPC line on Stalin, for instance, is “70% good, 30% bad”).
• In the 80s, some Warsaw Pact countries (possibly just East Germany) were on par with or ahead of the West on LGBT rights, policies that came to an end with the dissolution of the USSR.
• Post-Soviet Russia is a capitalist state likely more corrupt and undemocratic than even the U.S., and I’ve seen no Hexbear user defend it, much less its reprehensible stances on LGBT rights. What you will see, however, is discussion of Russia’s actual intentions (not propaganda like “Putin is a mustache-twirling villain who does bad things for no reason”) and its role as a counterweight to NATO hegemony.

It’s also important to consider the USSR’s stance on LGBT rights in context of the rest of the world – they were still wrong to oppress LGBT people, but no one else was doing much better, which indicates those bad policies were not some unique aspect of socialism. Cuba, for instance, just passed a Family Code that has LGBT protections far ahead of anything the U.S. has at a national scale, and the public support programs of socialist countries (housing, education, labor protections, etc.) are significant benefits for any marginalized community even if not expressly intended as such.