https://www.opendemocracy.net/digitaliberties/chenchen-zhang/curious-rise-of-white-left-as-chinese-internet-insult
If you can read Chinese:
https://www.zhihu.com/question/51331837
It might not be an easy task to define the term, for as a social media buzzword and very often an instrument for ad hominem attack, it could mean different things for different people. A thread on “why well-educated elites in the west are seen as naïve “white left” in China” on Zhihu, a question-and-answer website said to have a high percentage of active users who are professionals and intellectuals, might serve as a starting point.
The question has received more than 400 answers from Zhihu users, which include some of the most representative perceptions of the ‘white left’. Although the emphasis varies, baizuo is used generally to describe those who “only care about topics such as immigration, minorities, LGBT and the environment” and “have no sense of real problems in the real world”; they are hypocritical humanitarians who advocate for peace and equality only to “satisfy their own feeling of moral superiority”; they are “obsessed with political correctness” to the extent that they “tolerate backwards Islamic values for the sake of multiculturalism”; they believe in the welfare state that “benefits only the idle and the free riders”; they are the “ignorant and arrogant westerners” who “pity the rest of the world and think they are saviours”.
It's basically a term the Chinese use to trash people online.