you can not amend 2021 because the amount was not paid back until 2022.
you have two options in 2022
since the repayment was more than $3,000 you
1) can take as a deduction on schedule A line 16 denote as IRC 1341 repayment OR
2) recompute the taxes in the year (2021) you received the overpayment by excluding the amount repaid from income.
the decrease in taxes is taken as a credit on schedule 3 line 12d denote as IRC 1341
