this is the first I've heard of it, and I've spent some time on 4chan. Frankly I'm skeptical. 4chan already blocks you from uploading images that have extra data embedded in them.

EDIT: To add to this, how 4chan actually doxes people is very different. They typically post one very large image, which is a detailed collage of images with bits of information relating to the subject they are trying to identify. This is so the image can be easily downloaded and reposted. They did this a lot to help with identifying Antifa vandals a year ago.