Typically, you can expect to get a letter from the IRS in the next 3-4 weeks explaining things. If I were to guess, I would say you're probably self-employed and you made a $500 quarterly tax payment at some time in 2021 to the IRS, that you forgot to enter on your tax return. Therefore, you overpaid your taxes by $500.
But regardless, you can expect a letter in the next 3-4 weeks. Meanwhile, I'd suggest you not spend that money until you "know" you can keep it.
