Since you received it in 2025, if it is income, it will be reported on your 2025 return.
Was this a state refund? If yes, did you take the Standard Deduction on your 2023 Federal return? If yes, the 2023 state refund will not need to be reported, it is not taxable.
The reason is that if you take the Standard Deduction on your Federal return, you are not deducting state tax paid on Schedule A. Since you did not deduct state tax paid, you don't claim state tax refunds.