How do you know? Perhaps the very act of walking into a white-owned business while black means that one will experience a lesser quality of service. We who are black know that it happens more often than not.
So, BLM is asking for its adherents to shop black for a certain time during the high-spending holiday season. Is that really "hurting" white businesses? Don't most BIPOC have to spend their hard-earned dollars at white-owned concerns for the most part? We generally have little choice as the businesses at which most Americans spend money, period, are white-owned corporate ones.
I don't know whether you believe you mean well or if you're defending a toxic point of view for the sake of eyes. Whatever your intention, you got it wrong.