I recently received a 1099-r for the 2020 tax year. Considering it is now 2022, what do I do with this form? Can I file it with my 2021 return?

The 2020 Form 1099-R can only be entered on a 2020 tax return.  If you filed a 2020 tax return then you will have to amend the 2020 tax return that was filed to add the 1099-R.

See this TurboTax support FAQ for amending a 2020 tax return originally completed and filed using TurboTax - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return/00/27439

No. You would have to amend your 2020 return. If the amount is small you could wait for the IRS to adjust your return and pay some interest.