Multiple DC - You have been Disconnected because your account information has changed

[Dëj-pyrewood-village]

Has Blizzard been hacked or something?

I have had 7 of my guildies DC tonight and receive this message.

“ou have been Disconnected because your account information has changed”

[Saneko-ragnaros (Saneko)]

Account information has changed

Hello i just got this message and disconnect “You have been disconnected because your account information has changed. (BLZ51900062) ” I never saw this error so dont know what happen or what to do. I have ultra strong password, physical authenticator bought in 2012 (yes still working) and phone protect. Nothing was changed in my account and i can log in back.