I'm still trying to wrap my brain around this.  In prior years there was a 2-page worksheet buried in the 1040 general instructions for calculating the limitation on the child tax credit (see pages 38-39 of the i1040gi--2020.pdf  as an example).  Did PS Basic produce that worksheet?  I'm pretty sure Pro did and at one point I made a determination that it was required for due diligence so I always included it in my DueDoo "bundle" along with copies of any documents I relied upon and client Q&A.

For 2021, the IRS moved everything to the "new and improved" 3-page Schedule 8812.  The worksheet is no longer in the i1040gi.pdf but is instead in the i1040s8.pdf.  The limitation (or at least one of them) is now calculated on S8812 Line 5.  There are four other worksheets in those instructions which may or may not be relevant depending on circumstances.  I think the Line 5 is always relevant, if nothing else it's $3,000 (or $3,600) x # of children which IMO is certainly part of "determining the amount" of the credit.

Does PS Basic (or Pro) still produce a version of the "old" worksheet?  Or is the math truly just buried in the software without showing any work whatsoever?  I think that's a potential DueDoo disaster.  I can picture the IRS auditor now:

Auditor: "And how did you determine this number you put on Line 5?"
Tax preparer:  Blank stare.  "I don't know.  The software does that calculation."
Auditor:  "That will be $545 please."