try the added lines

'http://skp.mvps.org/ppt00025.htm#2
Sub pvtReplaceText(sOld As String, sNew As String, Optional bWholeWord As Boolean = False)
    
    Dim oSlide As Slide
    Dim oShape As Shape
    Dim oText As TextRange
    Dim oTemp As TextRange
    
    For Each oSlide In ActivePresentation.Slides


        For Each oShape In oSlide.Shapes
            Call pvtReplaceText1(oShape, sOld, sNew, bWholeWord)
        Next oShape
    
        'added 6/17/2021
        If oSlide.HasNotesPage Then
            For Each oShape In oSlide.NotesPage.Shapes
                Call pvtReplaceText1(oShape, sOld, sNew, bWholeWord)
            Next oShape
        End If
    Next oSlide


End Sub