Identifying Textboxes the have "Text Autofit Improvements"

The storyline release notes and discussions about autofit seem to indicate that it's not just the textboxes that are updated but the entire project itself is set this way. I believe this means that you wouldn't be able to delete those slides and in my version of 360 there isn't a way to convert back to the non-autofit version of a project once you've converted it over. 

In the notes about autofit storyline seems to know this and it mentions that a backup copy should be saved if it's needed in previous versions.

https://articulate.com/support/article/Storyline-360-Text-Autofit-Improvements#:~:text=in%20case%20you%20need%20to%20access%20it%20in%20Storyline%203

https://articulate.com/support/article/Compatibility-Between-Storyline-360-and-Storyline-3-Project-Files#:~:text=feature%20won%E2%80%99t%20open%20in-,Storyline%203,-or%20earlier%20versions%20of