I have seen two other non-resolved issues of this type in my initial forum search. A customer purchased a gift card on 12/20. I received the PayPal notification of the sale with the correct invoice ID, but neither Magento sales reports or the gift card extension report the sale. There is no record of the sale anywhere. Other sales are reported correctly. There is one record of the amount in the Abandoned Carts section of the Marketing section of Reports, showing the initial cart created on 12/16 and updated on 12/20, the date of the sale. But no customer name or email. Both are supposed to be required fields. I am also contacting the gift card extension support and PayPal. But, for now, I have received payment for something Magento "thinks" never happened.
it seems like your PayPal Express review order page has some JS issues.
you need to check on the PayPal Review Order page.
to check that you need to place an order using PayPal & on the review page open the browser console.
you can also install the following browser monitoring tools which help to track User issues & journy :
https://newrelic.com/products/browser-monitoring
https://noibu.com/
https://www.hotjar.com/
kindly Accept as a Solution if this works for you and give Kudos
gift card developer is looking into it.
Have you had a resolution to this issue?