re: Is the rescission of the DACA executive order racist?

This is called Detrimental Reliance under the law, which is an equitable doctrine. The Dreamers believed, not being constitutional scholars, that Obama, as President, had the Authority to make the DACA deal, and no one got a court order declaring the DACA executive order unconstitutional.

The Dreamers, under equitable principles, thus should not incur detriment because they relied on Obama's apparent authority.