SteamTrain is correct. The only effect in TurboTax from omitting the marking of box 13 Retirement plan is that TurboTax will force some or all of a traditional IRA contribution to be nondeductible if your modified AGI exceeds a certain threshold based on your filing status. You haven't mentioned making any traditional IRA contributions (a 457(b) is not an IRA), so if you made no traditional IRA contribution for 2021, there is no need to correct anything.
