My 2020 return was rejected twice because AGI doesn't match 2019 return. Latest info on my IRS account shows 2018 info but not 2019. Should I file/refile 2019 return?

If the 2019 federal tax return was not processed by the IRS or you did not file a 2019 tax return, then enter a 0 (zero) for the 2019 AGI and e-file your 2020 tax return again.

   My 2020 return was likewise rejected due to non-matching AGI from my 2019 return.  Turbotax entered the incorrect AGI from my previous return that they filed.  You should simply enter the number that the IRS shows on file for 2019...  they merely use that number to verify your identity.