Lookup with more than one criteria

EllenKristina 

Another strategy is to blank out the dates with that correspond to the wrong currency and then use XLOOKUP to return the exact match from the remaining dates or, failing that, the next latest.

= LET(
      filteredDates, IF(CXRateTbl[Code]=[@Code], CXRateTbl[Date]),
      XLOOKUP( [@Date], filteredDates, CXRateTbl[Rate],"No match",1)
   )

Placed within the Transactions Table the formula will propagate down the column.  If used outside the Table one should aim at returning results as a dynamic array.  This require the use of MAP and LAMBDA to get the inequalities between two arrays to work correctly

= MAP(Transactions[Date], Transactions[Code],
      LAMBDA(date,code,
          LET(
              filteredDates, IF(CXRateTbl[Code]=code, CXRateTbl[Date]),
              XLOOKUP(date,  filteredDates, CXRateTbl[Rate],"No match",1)
          )
      )
  )