As someone who was educated in China for 11 years, I would argue the part of KMT that CCP left out in my history book was mostly covering up the corruption and incompetence of KMT.

For example, little did I know that KMT deliberately destroyed a dam to "stop" Japanese army that killed almost 1 million instantly and later caused a famine in Henan that caused between 288,006 and 1,484,983 deaths right at my hometown[0][1].

[0]: https://en.wikipedia.org/wiki/1938_Yellow_River_flood

[1]: https://en.wikipedia.org/wiki/Chinese_famine_of_1942%E2%80%9...

Edit: changed to English wikipedia pages from Chinese