You don't need to do anything with the Form 4549 for you 2021 tax return, unless the changes affected something that carries forward from 2020 to 2021. For instance, if you had a capital loss carry forward from 2020 for 2021 and that amount was changed by the IRS, you will need to update that amount in your 2021 return. If the changes only affected 2020 amounts, you don't need to do anything.