is evaluated differently in Dynamic-Array aware Excel vs older Excel.
In particular, the LEFT and MONTH functions don't return arrays to the formula in the older Excel, but instead only the interpolated row / column value.
It would be good to sort this out and document a bit.
Keywords would be "implicit intersection" and "dynamic arrays".
See https://exceljet.net/formula/xlookup-with-complex-multiple-criteria and https://groups.google.com/g/exceldna/c/bwXlP-OXfPM
If seems that a formula like
is evaluated differently in Dynamic-Array aware Excel vs older Excel. In particular, the LEFT and MONTH functions don't return arrays to the formula in the older Excel, but instead only the interpolated row / column value.
It would be good to sort this out and document a bit. Keywords would be "implicit intersection" and "dynamic arrays".