I removed the excess IRA contribution before the penalty deadline and there was Fed. tax withholding even if there was no earnings, how to report the Fed. tax withheld?

I made the excess traditional IRA contribution for 2019 in 2019 and removed it entirely in March 2020.  There was no earnings but loss from the removal. Even if there we no earnings, there was federal tax withholding. The relevant 2020 Form 1099 R will not available until January 2021. Should I report the federal tax withholding now in Box 4 of my made-up 1099 R for 2019 tax return?  Or should I leave Box 4 blank now for 2019 tax return and report the federal tax withholding next year for 2020 tax return?