Edit: this question has been answered now. Thank you to everyone who took the time to help me understand.
the premise that race is not a natural, biologically grounded feature of physically distinct subgroups of human beings but a socially constructed (culturally invented) category that is used to oppress and exploit people of colour.
Okay… But we can take a DNA test and get our ancestry, telling us what percentage of what races make up our overall ethnicity. So how is race a social construct and not a biological feature, when we have a scientific method to determine our race? This part of the philosophy has been bothering me ever since I read it, and I’ve been hesitant to ask because of how offensive people get when you question this system.
Not_Rick has a great answer but I will add something. Your question about the quote you posted is based on a disagreement about what race is, between you and social scientists. The phrase “we can take a DNA test and get our ancestry, telling us what percentage of what races make up our overall ethnicity” already assumes that genetics = race, end of story. But this is an unfounded assumption. All the test can tell is our genetics. Not_Rick offered some good examples for the counterpoint, that genetics ≠ race. If you disagree with that basic premise then you will always be bothered by modern theories on the subject such as CRT.
Once you see that race clearly is not just genetics, you can start asking what it truly is and what things do determine one’s race. These are much more interesting questions. For example, a new question might be ‘what has been the historical relationship between ethnicity and “being white” in the US’? And let’s not even start on the ridiculousness that is the census form.