Real slavery, like what's permitted via the Thirteenth Amendment and propagated by over-policing black communities? Pretty sure the "American Left" is keenly aware of this, even if terminally-online armchair policy analysts engaging in whataboutisms aren't.
This is kinda the whole crux of prison and police reform in the US; you may want to read "The New Jim Crow". Decent primer.
comparing this to what happens in USA is why people don't take BLM and DEI seriously