Gets "Pdf contains unapplied redactions" warning when the file has no redactions

My colleague uses ios and when I save a pptx to pdf and sends it to him, he gets a warning:

"This pdf contains unapplied redactions. To permanently remove the selected content, select apply"

My other colleagues on Windows do that get that. I've used other softwares to open the pdf file, and could not find anything wrong with it either. It is just a pptx saved as pdf, so there should be no redaction to begin with.

If anyone knows what's going on and has ways to combat it, it would be very helpful. Thanks