No, Brexit isn't the ONLY reason businesses are dying but it worsens other factors.
Neither a working class white or black person is 'privileged'. But racial discrimination (interviews, police etc) can affect one more.
This all-or-nothing approach to whether something is making things worse, is just not smart.
e.g.
The UK no longer being a logical base of EU-wide distribution might be just one of several key factors in a company leaving, but still a crucial factor.
Similarly...
I admit, "white privilege" is an inappropriate term to use in the context of poverty. But pointing to those in poverty in order to pretend racial discrimination isn't a factor that broadly affects society, and can help trap people in poverty...
Again, just not smart.