Received 1099-G for a taxable grant (box 6) from the EWF. They withheld $780 in state taxes and stated that federal income taxes may still be due. How do I enter this?

I put the $15,600 taxable grant under "other income" and state tax withheld in box 11 of 1099-g under "unemployment compensation".

However, it's stating I owe about $3k in federal taxes and $1k in state taxes which makes no sense to me.  The grant was for $15,600 and the state taxes were taken out before I received it. Please provide any guidance.