Writers write; reads interpret.

I'd bet we in this forum all know how Line Rebate Recover Credit on Line 30, 2020 Form 1040 is computed. 

Even if not, Lacerte would do it for us using the 2020 AGI, EIP1 and EIP2 info.  If the EIP info is left blank, Lacerte generates a diagnostic.  

In the earlier message, qbteachmt said: " Use their 2020 info, including the amounts received, for EIP 1 and EIP 2. Don't use any 2019 or earlier info",

I infer qbteachmt meant to TELL our fellow practitioners not to use 2019 or earlier info.  My "doubt" that 2019 info was in the picture was my confidence (based on my presumption) that they did NOT use the 2019 info.  I have made it clear how Lacerte computed RCC in the first few lines of my message.  Your interpretation of my line was way off...