Minh answered your question. " What you earned will be covered by a 1099-R for the following tax year and will be entered then as a normal 1099-R."
You don't owe tax on the earnings made by an excess IRA contribution in 2019, but you owe tax on them in 2020.
The reason is because these earnings were likely earned on both years (2019 and 2020) so the IRS lets you (and the IRA administrator) defer reporting it until your 2020 tax return.
So, in early 2021, you will receive a 1099-R that shows the earnings on the excess, to put on your 2020 return.
