Unknown transaction in bank statements?

Hey, my problem is this: I looked at my bank statements in the app today and saw that I transferred 41.95 to a Payoneer account a month ago. I can't remember such a transaction for the life of me because I definitely didn't consciously buy anything with that amount (I didn't receive any goods or anything like that). I also considered whether it could have happened by mistake, but I can't imagine any scenario, and I'm absolutely certain that I didn't intend to buy anything with that amount or even think about it. What should I do? I want to know what this was paid for. This makes me really sad because it's also the money from my summer job 🙁 It's probably irreversible anyway, I know.

BTW it is an Irish account which makes the whole thing even weirder

Thanks for reading 🙂