It is certainly discrimination. Evidence has been collected and judgements made, e.g. that African-Americans are severely discriminated against, and special provision be made for them to compensate.

This is specifically trying to be fair, rather than trying to make access equally difficult. I don't know why that is hard to grasp. I don't think 'righting injustice' is bad way to explain it.

Harvard is also discriminating against Asians because there are 'too many'. This seems quite likely but is a separate issue. The historical injustice is present, but cannot be said to have the same character. I don't think criticism of other minority AA programs is justified, but you can have your own opinion.

Earlier in the 20th century, that reasoning was used to limit the admissions of Jewish students. The issue was cast as their being admitted at a disproportionately large rate as compared to the general population, so corrective measures were implemented.

https://www.businessinsider.com/the-ivy-leagues-history-of-d...

Back then, there were zero black students at Harvard. The admissions process can’t become more fair by failing to correct for the vast injustices imposed on African-Americans. Arguing that Black students are taking what rightfully belongs Asian students is just as racist as Harvard’s anti-Jewish policies.