A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
This should work with an up-to-date copy of Powerpoint/Office 365; it doesn't work with non-subscription versions of PowerPoint (ie, PowerPoint 2021 or prior) though.
Sub LockSlideImagePlaceholders()
Dim oSl As Slide
Dim oSh As Shape
For Each oSl In ActivePresentation.Slides
For Each oSh In oSl.NotesPage.Shapes
If InStr(oSh.Name, "Slide Image Placeholder") > 0 Then
oSh.Locked = True
End If
Next
Next
End Sub