https://wccftech.com/galaxy-z-fold-3-galaxy-z-flip-3-protect-battery-feature/

All lithium-ion cells have a specific number of charge cycles after which they are unable to deliver the same battery life. To combat this, Samsung has introduced a new ‘Protect battery’ feature to the Galaxy Z Fold 3 and Galaxy Z Flip 3 to prolong the lifespan of the new handsets.

The latest version of Samsung’s custom Android skin, One UI 3.1.1 for the Galaxy Z Fold 3 and Galaxy Z Flip 3, might not bring a massive number of changes in terms of aesthetics, but it has introduced features intended for you to keep your device for a little longer. One of them is ‘Protect battery’, and according to the image uploaded by Sammobile, which can also be found by navigating into the ‘More battery settings,’ the maximum charge is limited to 85 percent.