That Dropbox retains data far longer than what can be considered reasonable. It's in the headline, of course, but I think that quote highlights the severity of it quite well.
Stated in the thread several times but I had files from 8 years ago appear. All of my devices had been replaced in that time so only Dropbox could have a copy. Definitely concerning that they keep files forever like this, I wonder if it would be caught if this bug didnt happen.