To rapidly lose your userbase to another platform, due to controversial changes to the website.

Named after Digg, which lost most of its userbase to Reddit and is now a shell of its former self.

Digg (a link aggregator very much like Reddit) started pulling similar shit and everyone left for the alternative, which was Reddit at the time.
After everybody left Digg, Reddit became the default and after about 15 years they are doing the same things that drove people away from Digg