If you open your filed return in TurboTax, before you start to amend it, I think you will find that it has recalculated it for the unemployment exclusion. It should match what the IRS did.
To open your return, at the Tax Home or in the section Your Tax Returns & Documents for 2020, look for a link "Add a State." Click on Add a State. You don't actually add a state. This is just a way to get back to your 2020 online tax return after it has been filed.
