According to the following IRS website, the refund can be used to offset any federal tax debts.
https://www.irs.gov/newsroom/2020-unemployment-compensation-exclusion-faqs-topic-g-receiving-a-refun...
Q4. If the exclusion adjustment results in a refund, will the IRS use the refund to pay (offset) any unpaid debts I may have? (added April 29, 2021)
A4. Yes. Unpaid debts include past-due federal tax, state income tax, state unemployment compensation debts, child support, spousal support, or certain federal nontax debts, such as student loans. If the refund is offset to pay unpaid debts, a notice will be sent to inform you of the offset.
