Scam? Not understanding this

Hello,

For Xmas, we purchased a couple Amazon gift cards for friends. Randomly today, we got a. Email Saying one of the cards was being refunded and said "item not satisfactory"

I don't understand what is happening here. What is this scam? Did someone gain access to my account and request this refund to test out their access?

And what happens now when my family tries to use the card I gave them?

We have changed password and removed payment methods from the site, but is it too late?

I appreciate any advice.