Why does it take so long for a customer to receive their refund?

What’s causing the delay?,because how can I pay for an order with a vendor if I haven’t received the payment from the customer

so if my payouts are set to every business day that means I will receive the payment the next day ?

My payouts are set to every business day so doesnt that mean every 24hours I will receive a payment

How long does it take a payout to deposit in your bank (USD) ?