This has happened on various devices in many different countries and regions. Even the Galaxy S10+ in the office had the weird notification in its shade. Tapping on it does nothing and it disappears as quickly as it appeared.
A lot of users were spooked, thinking that it's a hacking attempt at their phone or that someone has hijacked their Samsung account. Don't panic — seeing as how widespread this is, it seems to be a server mistake at Samsung HQ. It just happened to send a notification to everybody — either it was a fluke or somebody pressed the wrong button.
Samsung's official statement on the matter:
Thanks for bringing this to our attention, Jan