The Fed is an accomplice to the increase in inequality. An accomplice is an entity that helps another entity commit a crime.
The real change that led to increased inequality is the conspicuous drop in labor share after the crisis. Record profits by firms were not being transmitted to labor. That was not the fault of the Fed. However, the Fed fed the situation by putting excessive liquidity into the capital income stream. The transmission mechanism to direct that liquidity to labor had broken down. The Fed knew that, but the Fed kept supporting the guilty ones who soaked up the excessive liquidity into capital income. In the end, capital income grew tremendously, while labor income didn’t. Inequality increased.
So the Fed is an accomplice to the rise in inequality.