I forgot about this topic. Make sure to read what I copied from the IRS "Known Issues" into this topic regarding Form 8915-F:

https://proconnect.intuit.com/community/proseries-tax-discussions/discussion/three-year-split-of-202...

Unless the IRS works on this later, it appears this will be a PDF form as attachment, for tax year 2021, and not provided as XML by the IRS. It is possible the 1099-R worksheet might accommodate entries. While I am a programmer that understands XML, I don't work for Intuit.