A customer pays for a $200 service using Bitcoin. Between the moment the customer checks out and when the business receives its settlement, the Bitcoin price drops by 8%. How much does the business receive?

The rate is locked the moment the customer checks out. After that point, the processor owes the business the agreed dollar amount. What happens to Bitcoin’s price in the meantime is irrelevant, because the conversion already happened at checkout. This is the mechanic that removes volatility risk for merchants: the business is not exposed to price movements because it was never holding the crypto. The dollar commitment was made at the moment of sale.