Appraisers don't set the market price, buyers and sellers do during transactions.

Appraisals depend on the other transactions in the area that closed. If the offer is way above that average the appraisal will come in low.

There is a reinforcement effect from low sales prices on comps to low appraisals to lower approved loan amounts back to lower sales prices. The way out of this cycle is "cash offers". When wealthy people come in and throw cash down, prices rise and appraisals do too.

Minority communities don't have the stock market wealth that other communities do. The last decade of rock-bottom rates has increased the wealth of the already wealthy faster than those whose we wealth is tied more to their family home.

It isn't redlining although it is a really problematic economic situation.