Note 8 september Security update recieved....

dont know what this update is about ... march security patch is already running on my device ,, if anybody knows please let me know

My note 8 battery was doing good job after the oreo update , it was roughly 13.5 hoursnow from last 2-3 days , it has been reduced to just 11.5 hours or even 11 hours please help , what will be the issue ?

my update is downloading via smart switchdownload size is 4051 MB

please please never buy any samsung phone in future ,,,, I am having note 8 , gonna sell it as soon as possible ,, go for other brands ,, they are far far better than samsung jn terms of performance & timely updates ....