Files get corrupted with patterns of one page on every page which are transparant.
This usually happens in artboards. So I'm just designing, making pages, and then I move an image, or I do something, and I press ctrl+s and see that my current page has random translucent versions of my original design. say if I have a butterfly on my current layer, ALL OF THE PAGES will have the same butterfly PATTERENED over them, most layers will have it, and I save it and it becomes a raster image. the pattern becomes a raster image which I can erase. so I have to sit there, ERASING IT FROM EVERY LAYER THAT IT HAS RANDOMLY APPLIED TO. It's like if one has it all of them will 100% be corrupted. this has happened multiple times.
Here is an example of an article with a text image.