Apple is not a bank, doesn’t handle funds during an Apple Pay transaction and doesn’t participate in Apple Pay refunds, because their is no such thing.
Refunds are between the merchant, merchant’s credit card processor, merchant’s bank and your bank. If/when Uber eats processed your refund it would have created an ARN or Acquirer Reference Number. Please contact Uber Eats support and ask for your ARN. If they don’t have it, they never started the refund. If they provide the ARN, contact the bank that issued your debit card and provide them the ARN and ask them to trace the transfer.