The system message that a user gets when their premium membership is expired is sent out multiple times over a short time span, as seen below:
All the same message, all the same timestamp, just repeated six times.
This occurs when your premium expires. This has happened two times before on my end. All you have to do is get premium 450 and it will happen at the end of your premium time.
This happens on PC, Windows 10, Chrome.
This started happening 2 months ago.