help fixing my macro from running multiple times

I have some isssues with a macro that I am running. I have the following code:

Dim r           As Range
    Dim cell        As Range
    Dim Nextrow     As Long

        Set r = Intersect(Target, Range("B10:W41"))
        If r Is Nothing Then Exit Sub
        
        ' Next available row
        Nextrow = Worksheets("Transition Sheet P-S").Range("A" & Rows.Count).End(xlUp).Row + 1
        
        For Each cell In r
            With cell.EntireRow
                If UCase(.Range("M1").Text) = "YES" And _
                   WorksheetFunction.CountA(.Range("B1:V1")) = 21 Then
                        Worksheets("Transition Sheet P-S").Cells(Nextrow, "A").Resize(1, 21).Value = _
                                                                              .Range("B1:X1").Value
                    Nextrow = Nextrow + 1
                End If
            End With
        Next cell

It keeps pasting the same row over and over if I click on that line again if I click back onto the row. I would like to maybe change the way the macro is being triggered can someone explain to me how to do this or show me code that will fix this issue?