There were a number of ways in which “policies” connected to World War II affected minorities. There were also ways in which things that were not really policy also impacted those groups.
Of course, the most notable policy that impacted a minority group was the policy of interning people of Japanese descent living on the West Coast. This was a policy of the government that ended up causing massive disruptions to the lives of these people. It also caused many of them to lose their property as they were forced to sell before being interned.
Another actual policy that mattered was the military’s policy of segregation. For example, the Navy only allowed African Americans to serve in menial positions. This policy (along with possibly racist attitudes on the part of their white officers) helped to create the Port Chicago disaster in which more than 200 African American naval enlisted men were killed in an explosion on an ammunition ship that they were loading in California.
Minorities were also impacted by the war in general. In particular, African Americans were impacted because more of them came North in search of jobs in war industries. This continued the “Great Migration” that had started in WWI.