Title, I'm a leftist but after reading some things on lemmygrad and here it seems I might have been lied to all my life. I have talked with some people from Cuba and Venezuela (expats) that support the west narrative about poverty and mismanagement. I "believe" that Russia is attacking Ukraine for selfish reasons and that China censors access to foreign information using the Great Firewall, please prove me wrong. Furthermore, it ultimately depends who do you want to believe or there are hard facts from reputable sources that are simply a hidden by the mass media?
EDIT: Thanks everyone for your very civil responses. I'll answer as many as I can!
People have mentioned restricting western ideology and propaganda, but imo the more important reason for this is money. The PRC doesn't want all the potential money in tech and social media to fly across the globe to California. "Global" social media are nearly exclusively based in the US.