This was through Jetpack. My mistake if I have incorrectly associated the two, as I thought Jetpack came pre-installed with the WordPress software.
I have already disabled all plugins AND changed the theme. Ads were still present.
What I’m trying to do is clean up my media library, and I’m needing to know when it’s safe to delete an image from the library. Some images are being replaced, while others are being removed altogether. But I need to know where the instances are so there isn’t the obvious blank space where an image should be.