How do I report an excess SEP IRA contribution which was withdrawn (+ earnings) before the tax deadline. The 1099-R wont be available until next year.

I contributed during 2020 and noticed it was in excess of the allowed amount in 2021.  The full amount with earnings was withdrawn, but it was done so after 1099-Rs went out.  I talked with Betterment support and they said 1099-Rs are sent for the year the transaction occurred, not the year the contribution was made.  But it seems like the IRS wants it reported now to avoid a penalty and I'm not sure how to report it without the 1099-R.  I know the capital gains amount but have nowhere to enter it.