Use of Co-Pilot to review academic papers - does it add to similarity index on turnitin software checker

Hi, I am currently a student at a South African university doing my Phd. I would like to use co-pilot to review my chapters and journal articles to give me feedback on it which means I will be uploading these documents onto co-pilot. Please advise whether documents that are uploaded on co-pilot is treated as confidential and secure? By me uploading my documents would this be available for turnitin software to pick it up that I uploaded the documents and it is available on the net thus it would reflect when I do submit my final document into turnitin software as higher similarity index?