When to use TextFrame or TextFrame2 in VBA
According to Jon Peltier here: http://peltiertech.com/programming-excel-2007-2010-autoshapes-with-vba/
"The TextFrame2 member was added in Excel 2007 and gives better control over the formatting of the text. Because it is not backward compatible, I would recommend using the TextFrame object"
I'm guessing a similar situation applies in PPT.
In addition, TextFrame doesn't contain the property LanguageID in macOS, so you're forced to use TextFrame2. Be aware of that if you're working with that property in a cross-platform environment. I faced that problem in the past.