https://www.equalitylabs.org/castesurvey documents that 2/3 of Dalits in the USA report being mistreated at work. I'm only aware of one lawsuit about it. That was the CISCO case. No federal agencies got involved because it does not fall into race, color, religion, sex, national origin, age, disability or genetic information. Therefore discriminating by caste is legal under federal law.
California may be a different story. The case against CISCO is the only one ever brought. You can read about it at https://hulr.org/spring-2021/caste-in-cisco-understanding-ca....
Remember. Only case ever brought, when surveys indicate that 2/3 of Dalits are discriminated against on the job in the USA. And it is definitely legal under federal law.
In the absence of any case, ever, saying that it is illegal to discriminate on caste in the USA, it is almost certainly generally legal.