Time remaining Activity Monitor
For the past few days i notice something in my battery time normally at 100% it shows 12hour plus time remaining but for the past days at 100% it only showed 6hour time now at 68% it only showed 3hour time.
The time remaining is based on what your computer is doing. See that spike in energy impact on the left-hand side of your screenshot? That means your computer is working harder, and will run for a shorter period of time on battery.