The Civil Rights Act and related topics are part of the US Code (laws) [1] and are completely unrelated to DEI. The legal redresses available for discrimination have not changed whatsoever.
The Civil Rights Act is exclusively about equality of opportunity and requires affected employers hire without regard to race, religion, and other protected classes. So for instance universities using racial quotas was deemed unlawful precisely because of the Civil Rights Act.
DEI stuff was in a very different spirit that really ran against the ideals of the Civil Rights Act. For instance it compelled affected organizations to specifically endeavour to hire based on the race and other characteristics of applicants. It's not entirely clear to me why it wasn't tossed immediately as being in violation of the Civil Rights Act.