The holodomor (Ukraine genocide, yes a real one not a pretend Gaza one)
Read on the current Ukraine war, do you even support it?
Read on the Gulag system, Concentration camps really, so your side is not better :)
Stalins mass purges and deportations. No free speech, press, assembly, one party state rule. You want this?
Read up on Chernobyl, the cover up.
Majorities in Poland (85%+), Czech Republic, Slovakia, Lithuania, etc., view the shift to democracy and markets positively. Living standards, education, and opportunities improved. Ukrainians overwhelmingly reject it post-independence and especially after Russian aggression. Baltics treat Soviet era as occupation, not legitimate rule.
Because I suspect you are a socialist. Not in the sense of like me in Sweden, but an actual tankie one.