Thanks for posting in the Community!
Let me show you how to record a GST refund in GST tab and then match it to your bank feed.
Once done, go to Banking tab. QuickBooks Online will automatically find match if the date and amount on the refund matches on the bank feed and on the GST refund recorded in QuickBooks. You can simply click on Confirm or click on Find match to locate the GST refund recorded.
For more information, you can check on this article: Categorise and match online bank transactions in QuickBooks Online.
Let me know if you have any other questions and I'd be glad to help. Have a great day!