The most prominent cause is the refresh rate and the display resolution, if both are maxed out it'll really cripple the battery.
So most of the time, the refresh rate of my screen, along with the resolution is set to standard - for social media and binge watching.
I would bump them up once I start gaming.
Thanks for letting us know here, about your experience using your Samsung Galaxy S21 Ultra, having issues with battery draining faster in normal usage and apologize for the inconvenience it caused you.
You can submit an error report through Samsung Members app as follows:
Step 1. Long press Samsung Members icon on Apps screen and tap Error reports.
Step 2. Tap OK on agreement popup to send system log data.
Step 3. Select Symptom category "Power/Battery/Charging".
Step 4. Describe the problem in details and SEND.
How to submit an error report on Samsung Members app? | Samsung PH
Battery Optimization Tips, you may click the link below.
For more assistance, you may contact us on our online Samsung support channels below.
If the problem persists, immediately bring your device to nearest Samsung Authorized Service Center.
Hope this content is helpful and your problem gets solved.