Compensation used prewar prices then discounted to cap total payouts.

Evidence

In other words, the government’s goal was to compensate the enslavers quickly. The country was at war and fighting for its future existence; time was of the essence. The commission used prewar values from 1859 and 1860 as a baseline when sales were frequent, then reduced valuations so as to not exceed the $1 million maximum allowed by law. — Dorothy A. Brown, Getting to Reparations, 76