That is not true.  You do not need to attached a signed statement to the return in order to claim a QBI deduction.

I believe what you are referring to is the safe harbor statement found in Notice 2019-17.  It is not required to meet the safe harbor requirements to claim QBI, as is clearly stated in the notice. I doubt anything has been directly implemented yet, you would prepare your own statement and attached it as a pdf.  The requirements an be found on page 9 of Notice 2019-17:

https://www.irs.gov/pub/irs-drop/n-19-07.pdf