ByRow function produces two different results depending on whether row is range or array

Viz 

SergeiBaklan seems to have got to the bottom of the problem.  Yet another example of the failure of the Calc engine to address the problem of arrays of arrays (that is, 'normal' problems).  

I do not have much extra to offer; I was interested in trying to master the new AFE.  I decided that the problem is better suited to MAP, so bypassed the problem rather than addressing it.  Rather than showing the anonymous Lambda function on the worksheet, I defined a Named Lambda 'AverageLast7λ' in its Curried form, giving the worksheet formula

=LET(
    Values,  TAKE(SORT(Data), , -1),
    Sqn,     SEQUENCE(ROWS(Values)),
    MAP(Sqn, AverageLast7λ(Values))
);

AverageLast7λ
= LAMBDA(v, LAMBDA(a,
    IF(a<7,"NA", 
        AVERAGE(INDEX(v, SEQUENCE(7, 1, a,-1)))
    )
  ));

The SORT and AVERAGE formulas are different, but it is simply change for change's sake.