2020 1099-R Box 7 Code PJ - how to handle

Hi!  I received a distribution for excess contributions last year (t/y 2020) for a small amount.  I also received a 2020 1099-R with the gross distribution, taxable amount, and the small Fed and State Taxes withheld.  Box 7 has code PJ; so far, so good.

 

But code "J" says the amount is *taxable in 2019*.  Do I need to file an amended return for tax year 2019 against the return I filed last year (2020 for tax year 2019)?  The amount that was taxed is already being withheld by T/T in my t/y 2020 return as it was electronically downloaded completely for t/y 2020 return this past week.  I'm confused.