S1584800280884 , via OnePlus 7T , Jul 28, 2021 : Hi, I've been using one plus 7t for a year and the experience is good. But recently I've noticed that the battery doesn't last as it used to be even though I use the phone the same way from the time I picked it. And the brightness goes down for a while and comes back to normal automatically. I feel that after the new system update I'm facing this issue. Can anyone help me to fix this.