heard this claim - is it substantiated or propaganda?
Right. You have two concepts: law as written and law as practiced.
Law as practiced in the United States oppress black people intentionally.
What nobody can point to is how there is systemic discrimination by law as written or law as practiced in the PRC.
Black people getting funny looks when walking down the street in China is not the same as the mass incarceration and material dispossession of black people in the US