I received a notice of interest paid to me by the IRS. That's hared to believe, I know. what TurboTax procedure do I use to enter the amount?

actually, it was quite common for IRS 2020 refunds.  It was late in making refunds to millions of taxpayers. by law, it (actually the agency it works for the US Treasury) must pay interest.   such interest would have been included with your refund.

it's recorded as interest income - 1099-INT

payer US Treasury (not the IRS but you can use IRS)

the amount per the 1099 

The IRS took so long last year to pay refunds they paid interest on it.

Enter interest from the IRS like a 1099Int and put the amount in box 1.  Enter it manually and just enter IRS for the payer.  Don't enter any other info like the address or a EIN.

Enter a 1099-Int  under

Federal on left

Wages & Income at top

Interest and Dividends

Interest on 1099INT - Click the Start or Revisit button

Don't enter a bank or broker name and don't try to import it.  At the bottom pick -  Change How I enter my Form

Then on the next screen pick I'll Type it in Myself