попробовать:
=QUERY(A3:B, "select B where A !='' offset "&COUNTA(A3:A)-1)
или:
=ARRAYFORMULA(VLOOKUP(INDIRECT("A"&MAX(IF(A2:A="",,ROW(A2:A)))), A2:B, 2, 0))
или:
=ARRAYFORMULA(VLOOKUP(INDEX(QUERY({A2:A, ROW(A2:A)},
"where Col1 !='' order by Col2 desc"), 1, 1), A2:B, 2, 0))