If it is the item you sold yesterday, that was listed with Ebay's Simple Delivery.
So, the buyer paid Ebay directly for the label which they provided for you.
As the label was not used I believe that eventually, the buyer will be refunded - you won't be refunded for something you didn't pay for.
If you contact Ebay Customer Services, you can ask them to update the tracking to the method that you used.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)