Go back through your screens that reference the RMD's, when it asks How much of the $20,000.00 was a RMD? Indicate none was a withdrawal. See if this provides a solution to your issue. You weren't required to take an RMD this year because of COVID restrictions.
I had an issue with treating an IRA withdrawal as RMD caused when I incorrectly indicated that part of my withdrawal was RMD. When I did that, just deleting the 1099 would not fix the issue. I kept getting the "excess IRA contribution" penalty warning. I also had a screen that wanted to know the total of my IRA account as of 12/31/2020. I have been making RMD's for 8 years and have never had that question.
The ONLY way I resolved the issue was to totally delete everything and start all over. there was a programming switch that was turned on by one of my answers at some point and total deletion of all data was the only way to turn that switch off.
If it happens again, try just deleting the 5329 from your forms listing. The Form 5329 is used to compute various IRA penalties. If you get stuck in a situation, try just deleting the from from TurboTax. Try reviewing your forms in TurboTax and deleting the form causing the problem. While in your return in TurboTax:
That might help is you run into the problem again.