Hi, and welcome to the Apple (user-to-user) Community.
Re: "identify what happened to my refund on the last purchase that I did"
As we are all Apple users, like yourself in the Community, no-one here has access to your accounts or details to check this out for you. We'd like to help, however.
Apple Pay Refunds generally take the same time to appear as purchases from Apple:
"If your refund is approved, the funds will be applied to the same payment method that you used to buy the item. How long refunds from the App Store or other Apple services take to appear":
Check the status of a refund for apps or content that you've bought from Apple – Apple Support
Eg: says:
Store credit: up to 48 hours
Mobile Phone Billing: up to 60 days
All other payment methods: up to 30 days to appear on your statement.
"If you can't see the refund after 30 days, contact your financial institution".
Apple Pay's refund method: Get a refund for purchases made with credit or debit cards using Apple Pay - Apple Support
says:
"When the merchant processes your refund, it goes back to your payment card automatically".
If needed:
Apple Pay Support
Apple Pay - Official Apple Support
All the best :-)