Check your dates because in some places you say 2020 instead of 2021.
Here is what is supposed to happen. You make the withdrawal in 2020, you get a 1099-R for 2020, you report the withdrawal and pay income tax on your 2020 return. Then, when you make the repayment, you file an amended 2020 return to report the repayment and get a refund of the tax you paid.
In your case, if you make a partial repayment in 2021, you could file an amended return right away. Then if you make a further repayment in 2022, you would file a second amended tax return. I would probably not do this, due to the length of time it takes to process and amended return and the difficulty of filing a second amended return after a first amended return. So I would hold off filing any amended tax return until you have repaid all the money, or you have decided that you repaid all you feel like repaying.
If you did not report the withdrawal on your 2020 tax return and pay tax, you can expect to get a compliance letter from the IRS, this is going to cause you additional issues.
