Im not sure either as it is using both.

I have had a play with this and thought i would share what i have.

Please note that i believe this could be made simpler if you can modify the way the excel data is arranged.

Sub pp()

    Dim ppSl As PowerPoint.Slide
    Dim strPath As String
    Dim rCell As Range


    strPath = "C:\Users\A\Desktop\Report Format_VBA.pptx" '< your template location
    
    Set oPPTApp = CreateObject("PowerPoint.Application")
    oPPTApp.Visible = msoTrue
    Set oPPTFile = oPPTApp.Presentations.Open(strPath)
    Set ppSl = oPPTFile.Slides(1)
    
    With Sheet1
        ppSl.Shapes("TextBox 3").TextFrame.TextRange.Text = .Range("B2").Value
        ppSl.Shapes("TextBox 4").TextFrame.TextRange.Text = .Range("B3").Value
        ppSl.Shapes("Rectangle 7").TextFrame.TextRange.Text = .Range("B9").Value
        ppSl.Shapes("Rectangle 16").TextFrame.TextRange.Text = ""
        
        For Each rCell In .Range("B21:B" & .Range("B" & Rows.Count).End(xlUp).Row).Cells
            If rCell.Offset(, 1).Value = "y" Then
                With ppSl.Shapes("Rectangle 16").TextFrame.TextRange
                    .Text = .Text & rCell.Value & vbNewLine & vbNewLine
                End With
            End If
        Next rCell
    End With
    
    ppSl.Shapes("Rectangle 16").TextFrame.TextRange.Font.Size = 12
    
    With oPPTFile
        .SaveAs "C:\Users\A\Desktop\Report Format_VBA_Edited.pptx"
        .Close
    End With
    
    oPPTApp.Quit
    Set oPPTApp = Nothing
    Set oPPTFile = Nothing
    
End Sub
I did not use the check boxes, instead i looked for the letter "y" in column "C" to include as part of results.

I would change my Excel data so that every piece of text that is to be formatted differently on the pp presentation resided in its own cell.
I would also have the four results saved in four separate boxes on the presentation rather than one.

Hope this helps anyway