I'll preface this by saying this is a complicated topic, every article is biased in some way or shape, it's truly difficult to find accurate information online, especially since I live in the West and do not speak Chinese, therefore it's truly hard to find some stuff, and since this is a political subject, my answer might also be biased in some way, I'll not hide this, although I'll try my best to not let that happen.

So, during the Korean War, most of the UN/US soldiers captured by the Korean People's Army (KPA for short), were given to the Chinese People's Volunteer Army (PVA for short), the internment camp most of this POWs were kept in a place near the Yalu River, which is near the border between NK and China, their situation is mainly explained by what we call here in the West as "Leniency Policy", what it means?

The Leniency Policy was a different approach to deal with POWs, but before I explain it, you need to understand that before the war, the communist favor was all time high, therefore, the idea to proselytize these beliefs was accepted, even though we know that Communism is not a religion and it's entirely based on a scientific approach, this "deviance" from the norm, can be explained by the hundreds of years that religions like Confucianism, Buddhism, Daoism, etc., dominated Chinese culture and it's the foundation of their country, so...it's not too far fetched to understand why some of this favor was translated to the political cause.

So, what is the Leniency Policy? The best way for me to explain this is saying, an effort to through the use of psychological warfare, to indoctrinate POWs about communist ideas and history, through the use of regular study of political and historical communism, there was also a practice of asking the US POWs to write confessions about war crimes committed, some wrote personal war crimes they committed, others wrote about general war crimes committed by the country, such as the use of biological warfare (of course the US denied that), those confessions were used mainly as a propaganda, the POWs read this confessions in front of a camera and later it was broadcasted.

The leniency policy is called that because instead of the "normal" methods of torture and brutalizing the captured folk for battlefield information, it was used as a way to convert prisoners, we cannot simply say people weren't tortured, of course it happened, but it was NOT the intention; soldiers who accepted the teaching were offered better cells and rations, living an easier life inside the camps, according to the sources, it was devised into three groups.

• Progressives → Those who made the confessions, agreed to the interrogators and simply complied with the system in place, we can argue some were just faking it, but there were those who truly converted.
• Reactionaries → Those were the folk who vehemently refused to comply in spite of beatings and isolation, they believed themselves to be patriots and some were even members of the KKK, they considerate the progressives as traitors and conducted murders and attacks inside the camp
• The last are called the "play it cool" folks, who agreed to some stuff, refused others, but generally kept their head low and did not tried to attract attention to themselves.

This the best answer I can give about this, the sources will go a lot more in-depth, but in order to truly grasp the situation of POW's during the Korean War, one needs to analyze both sides of the conflicts, if you want a thoroughly complete answer to your question, the US side of things need to explained as well, I could explain it, but since you did not specifically asked for it, I'll not write.

Oh another thing to keep in mind, some things are impossible to verify, there is some information China never released, North Korea is the same, so...any answer will come short in a few areas. Hope this is decent!

Sources:

• Powell, T. (2021). Road to Empire: POWs and Total War in Korea. Socialism and Democracy, 1–50.
• The Hijacked War: The Story of Chinese POWs in the Korean War. By DAVID

CHENG CHANG. Stanford, Calif.: Stanford University Press, 2020.

• Fitzpatrick, Meghan (2019). ‘Hard, primitive and below the belt’: The Korean War, Prisoners of War, and Training for Conduct After Capture. War in History. (I truly hated this source, but hey, I'll list it here anyway)