I agree. It sounds very much like an employment relationship - the fact that you can't/don't feel able to choose your own projects is a big red flag here.
If this were a standard situation within Europe/the EU, I'm confident you would be entitled to claim the rights of employment, including e.g. paid holiday. It's possible that this right would extend to a Chinese employer, although I'm not sure.
If you are genuinely self-employed, you should also have the freedom to employ other people to cover your work.
In fact - it isn't racism, according to the link you have provided.
"Racism is the belief in the superiority of one race over another."
Superiority is a key word here. The link actually ends up on the page for supremacism:
"Supremacism is an ideology which holds that a certain class of people is superior to others, and that they should dominate, control, and subjugate others, or are entitled to do so."
If this were a standard situation within Europe/the EU, I'm confident you would be entitled to claim the rights of employment, including e.g. paid holiday. It's possible that this right would extend to a Chinese employer, although I'm not sure.
If you are genuinely self-employed, you should also have the freedom to employ other people to cover your work.