I hope they do since it’s a real mess has anyone seen this anywhere else?
To answer my own question from IRS FAQ
Q A11. Will the IRS send me a letter of my advance Child Tax Credit payments to help me claim the correct Child Tax Credit amount on my 2021 return next year? (added June 14, 2021)
A11. Yes. In January 2022, the IRS will send you Letter 6419 to provide the total amount of advance Child Tax Credit payments that were disbursed to you during 2021. Please keep this letter regarding your advance Child Tax Credit payments with your tax records. You may need to refer to this letter when you file your 2021 tax return during the 2022 tax filing season.
For more information regarding this letter and how to reconcile your advance Child Tax Credit payments with your Child Tax Credit on your 2021 return, see Topic H: Reconciling Your Advance Child Tax Credit Payments on Your 2021 Tax Return.