Show a Variance

Tony2021 

I hope I'm interpreting this request correctly (If you're looking to use VAR, the solution can be adjusted).

My solution summarizes the actual data by month (Pivot not used) and then does: Actual - Forecast

'Header - an array constant
={"Date", "Variance"}

'Months - a unique list of months from the actual table. Properly formatted.
=UNIQUE(TEXT(tblActual[Funding Date], "mmm-y"))

'Lambda 'Diff' - it obtains the forecast for a given month by looking up the unique date in the forecast table.  It obtains the actual amount by filtering the actual table by that same unique date.  SUM the results to reduce to 1 value.  Finally,  HSTACK stack the date, and the result of Actual-Forecast.

=LAMBDA(a,v,LET(
    fcast, XLOOKUP(v, tblFC[#Headers], tblFC),
    actual, SUM(FILTER(tblActual[T. Amt of Draw], TEXT(tblActual[Funding Date], "mmm-yy") = v)),
    VSTACK(a, HSTACK(v, actual - fcast))
))

Sheet level formula:
=REDUCE(Header,Months,Diff)