The color of the people attending church does not really matter. Often it is a matter of where people live. It’s similar to whether someone attends a Pentecostal church service and an Presbyterian service. There are blacks and white who attend both. Other than that, it’s merely a way for man, looking from the outside to see how there are outward differences between one and another. There really is no segregation of the races in Bible believing churches, however, as some may claim, as in people are kept from attending or walking into a church. They may, whether intentional or not, be made to feel uncomfortable, or just not be comfortable in that service, which is often a problem in some churches.
There are relatively rich churches and relatively poor churches. There are Asians churches that speak Asian languages. Are they segregated from other believers. No. Some denominations were formed because blacks were not allowed in some congregations, like the Southern Baptist. That has all changed, however, for the most part.
It’s important to not make more of this than what the Bible does, which is easy to do.
There is no real distinction between the races in the Bible, in that God is the same God of all. He makes no distinction in his grace and favor in how we look or the color of our skin. There difference is in how we perceive things, especially in the United States, where there is a heightened sense of what people look like, the color of their skin.