Mao Zedong, the longtime Chairman of the Chinese Communist Party and the founder of the People’s Republic of China, was reported to have expressed his gratitude to the Japanese military and political figures who visited China in the 1950s and 1970s. Mao said that the Japanese invasion of China had united Chinese people and allowed the Chinese Communist Party to win the Chinese Civil War.
In the 21st century, these remarks by Mao caused strong reactions on the internet in China. With the 2020 Hong Kong Diploma of Secondary Education Examination (HKDSE) history subject controversy on the historical understanding of Japan’s invasion of China, these remarks have returned to the spotlight on Hong Kong and mainland Chinese websites. The word “thanks” expressed by Mao has been also interpreted by some observers as dark humour.


I understood what you mean, but I still think people are trying to twist his words, especially in these times of conflict between China and Japan.
In reality he says (according to that article):
And also:
He’s basically bragging about his country, his own people and their victory, but in a diplomatic way.