Unlike the Nemedian foundation issue you’re discussing, this rollback hasn’t been acknowledged nor has a reason been given for the issue. While the former is awful and I feel for everyone who did lose their progress, it wasn’t left up to mystery. Just because something worse happened to someone else doesn’t mean anyone who experiences something “less bad” should ignore it. (This is also an official server so it’s highly likely that some of the same people impacted by the Nemedian issue have now experienced a rollback, perhaps losing work towards replacing the damage done by the first).
That said, I have a private server. G-Portal recently moved my server from one bit of hardware to another. I’m sure other servers have been migrated as well, date range for migration between august 2 and august 20, though which ones and when each would be moved would only be known by whoever the server owner was that got the email. It wasn’t supposed to affect playtime/save progress (per the email I received) but things can go wrong. I wonder if something like this might have caused your issue as well.