I’m not surprised. The USPS employees, at every level, were heavily involved in the 2020 stolen election. If you’re comfortable committing one crime, then moving on to another isn’t a problem.
I sent a few gift cards through the mail at Christmas and felt a little hinky when I mailed them. Handling an envelope, it’s easy to determine if a card is inside.
When I mail gift cards, I go the extra mile and send them priority or express. I load the envelope with stiff paper so it can’t be felt through the envelope. I make it appear as though it is a set of documents, not a gift card.
P.S. The USPS won’t refund the gift card if it’s lost or stolen. Just the price to send it.