capitalist countries who were "relieved from extreme poverty" during their industrialisation period

Uh... Have you opened a book in your life at any point? Have you ever heard of these things called "British Empire", "Portuguese Empire", "Spanish Empire", "Colonial Africa", or "British Raj"? How about child labour in Britain during industrial development? Bengal famine, Irish potato famine, genocide of Latin Americas, slave trade... The list of actually enforced hunger and genocide is absolutely endless, and much more harrowing than the consequence of (admittedly disastrous) uninformed ecological policy in the mid-20th century.

All those people who were “relieved from extreme poverty” in such settler nations chose to do so on the backs of indentured servants who are not counted in your statistics, as white men tended to often exclude in consideration when formulating convincing metrics to justify their behavior.

Funny how extreme poverty starts racing down as soon as China adopted capitalist market reforms

Extreme poverty was already racing down in the times of Mao before Dengism, life expectancy in China rose some 25 years under Mao. What part of "attracting foreign investment increases the material wealth of the country when done under communist rule" seems funny to you? Is that some sort of gotcha against communists? Because it's literally the Marxist strategy of Dengism, outlined clearly and not hiding anything.

why is China covering it up

China isn't "covering up" the Tiananmen revolts, it's preventing the fabricated set of lies by western media to harm its country, and it's doing this successfully. China has historically been less developed than western countries due to late industrialisation and being a victim of colonialism and imperialism, and weaker countries need to apply state power to prevent foreign interference, as the Zapatistas had to learn during their struggle. As China strengthens and the West debilitates, China is capable of opening up and controlling its narrative with more soft power, and the West needs to crack down against journalistic freedom. We see this in the US with the banning of TikTok, and in the EU with the banning of Russian media.

Like what's going on in Xinjiang?

It's been five years that you libs have been propagating this misinformation about Xinjiang and there's still not a fucking shred of evidence. The education centres were closed years ago, the counter-terrorism campaign in Xinjiang was ssuccessful, and Xinjiang is not only developing, it's doing so at an impressively fast rate, and recently the Uyghur became the majority ethnicity in the region. You can literally go into your phone and look up how many Palestinian children have been slaughtered this past week by Israel with video evidence of pretty much every single case, yet in China, a country where pretty much every single citizen owns a smartphone and VPN use isn't persecuted (personally been in China and used VPNs to bypass the Great Firewall without issues), there isn't a single picture or video evidence of abuse of authority against Uyghur.

When in 5-10 years it becomes common knowledge that the Uyghur "genocide" was a western fabrication, remember that communists somehow always knew, and reevaluate whether you're just a propagandised cog in the machine. Everyone also "knew" about the weapons of mass destruction in Iraq and believed Nayirah's testimony in congress.