It's a bit rich, people complaining that they are discriminated against...when they aren't even legally allowed to work here in the first place. As of 2017 the laws have changed
https://teach-english-in-china.co.uk/what-the-new-chinese-work-visa-requirements-mean-for-you/

"Demand for foreign English teachers in China far outweighs supply. Therefore, you may still find that some schools claim the ability to employ non-native speakers as English teachers. Approach this with caution; the new regulations state that this is strictly illegal across the whole of China."

"In the past, non-native speakers with a high level of English were eligible to teach English in China. In fact, European passport holders made up a large percentage of our foreign teacher community. This unfortunately changed in April, thanks to a country-wide law banning schools from employing non-native foreign English teachers. This rule is not designed to discriminate, rather it is to ensure students are exposed to native accents. The same rule applies to teachers employed for teaching any foreign language"