We can be critical of the mistakes of past socialist systems without falling into the trap of believing every red scare era lie about them.
Absolutely! But we should also own up to the mistakes that really happened. China did turn to markets, because capitalist world once again got a critical share, and the benefits of international trade could hardly be overlooked. Tiannamen square massacre really happened, as documented in many instances. The conversion happening in Xinjiang is barely peaceful. USSR really did send insane amounts of people to GULAG, despite the scale of this atrocity often being overblown by liberals (but even still it’s massive), and really did forcefully move entire nationalities.
Don’t get me wrong, by any means, I do not denounce USSR or China and the roles they took in building a better future for everyone. In fact, the achievements they’ve made forced governments around the world to improve working and living conditions of the people - people that saw what the world could actually be. And inside countries, socialism has caused immense economic improvements - though, it must be said, the turn in both USSR and China was cruel and radical, which caused a lot of massive supply problems, famines, and more. But at the end of the day, they truly emerged the powerful forces on the world stage, and this really was an economic miracle and victory of the people.
If I would personally assess the heritage of the socialist era, I would say it was a massive win for the world. But if we want for the socialism to finally take over the world, we need to be fair with ourselves and others on the shortcomings of the bygone times. At the very least, not to repeat them again.