M Symbol in the notification area

It seems the main goal is to remove this notification icon. This is most likely caused by Secure Zone

Secure Zone creates an alternate user account which you can run
simultaneously with your ‘Open Zone’ (Regular account).

One feature of secure zone is cross-zone notifications:

Cross-zone notifications: Notifications from Secure Zone are displayed
in Open Zone with a small red dot to differentiate between the two.

Resolution

To get rid of such notifications, you have to delete secure zone:

• Switch to secure zone, pull down the status bar, press and hold "secure zone" icon, enter secure zone settings screen.

  
  



• Press menu key, and you can see a "delete secure zone" menu.

  
  

  

  
  

Hope this helps

Credits: Lenovo K920 Vibe z2 pro Secure Zone