In general, battery performance optimization is applied by learning the battery usage pattern after initial use after purchasing the product or OS upgrade. During the period of learning the initial battery usage pattern, you may feel the battery drain quickly. If the battery is consumed continuously for a long period of time, it may be another factor, so please check the following additionally.
When running multiple apps at the same time, running games or apps that require high resolution and high performance, and turning on auto-sync and Wi-Fi, Bluetooth, GPS, etc., the battery will drain quickly. It’s recommended to optimize battery usage time by setting an Adaptive battery or adding unused apps to sleep depending on your usage pattern. Follow the below steps:
Settings >> Battery and device care >> Battery >> More battery settings >> Turn Adaptive battery on.
The gestures recognition area of Android 11 has been updated to prevent accidental touching of the keyboard. When gesture hints are turned off, the gesture area has been adjusted because an error may occur, such as the keyboard being closed while the gesture is operated when a key is an input at the bottom of the keyboard due to interference between the lower gesture area and the app area. And if you turn on gesture hints and use them, the recognition area becomes wider -
To turn gesture hints on/off : Settings >> Display >> Navigation bar >> Gesture hints.
Also, try to update all the apps using Galaxy Store / Google Play store as mentioned by 707Hellcat.
I would suggest like cassidy has, backup your phone with smart switch & factory reset.
I'm not sure if your phone has the same settings for the navigation gestures as the S20 Ultra? but with one ui V3.0 on mine, there's also an option for side gestures, so make sure it's on or off depending on your preference.
But I have noticed occasionally that the bottom gestures stop working & I'll have to switch to navigation buttons & then back to gestures. My phone is expecting an update on the 26th of January, so hopefully it will be resolved.