I don’t add a tracking cookie or do anything with Imgur. People use Imgur to add images to their comments. Could that be it?

Good point, could be. But if that's the case, then said image must have been removed, as the cookie (as reported by EFF Privacy Badger) is longer being reported, so between the time of my post and the time of my first comment, something changed. Thanks for the reply.

Humm... this cookie has just vanished! So, something has changed, somewhere.