Hello @carloxvii
I have the same problem with my flow saving an attachment to a SharePoint.
My problem is that the save file does not open with this error:
"Cannot open this workbook because the file format may not match the file extension."

I also noticed that my flow tries to save the file twice with the "Apply to each" action.

And in the version history of on SharePoint, I find that there are two versions but not with the same file size.
Do you have any idea about the cause of this problem? and potential solutions?
I tried your solution with no success
Thank you in advance for your feedbacks!