Private Sub Worksheet_Change(ByVal Target As Range)
    If Target.Cells.CountLarge > 1 Then Exit Sub
    Dim sTarget As String
    sTarget = Target.Value
    If IsEmpty(sTarget) Then Exit Sub
    If IsNumeric(sTarget) Then Exit Sub
    If Target.Row = 1 Then Exit Sub
    
    Dim arr As Variant
    arr = Cells(1, 1).Resize(Target.Row - 1, ActiveSheet.UsedRange.Column + ActiveSheet.UsedRange.Columns.Count - 1).Value
    
    Dim ya As Long, xa As Long, dSum As Long
    
    For ya = ActiveSheet.UsedRange.Row To UBound(arr, 1)
        For xa = ActiveSheet.UsedRange.Column + 1 To UBound(arr, 2)
            If arr(ya, xa) = sTarget Then
                If IsNumeric(arr(ya, xa - 1)) Then
                    dSum = dSum + arr(ya, xa - 1)
                End If
            End If
        Next
    Next
    With Target.Cells(1, 2)
        If .Value <> dSum Then
            Application.EnableEvents = False
            .Value = dSum
            Application.EnableEvents = True
        End If
    End With
End Sub

=ARRAYFORMULA({UNIQUE('06.2026'!I2:I70)\SUMIF('06.2026'!I2:I70; UNIQUE('06.2026'!I2:I70); '06.2026'!H2:H70)})