There are many reasons that iPhone battery dies quickly:
1. The capacity of iPhone battery is relatively smaller than Android phones, so it “seems” to die quicker.
2. Too much software in the background. After iPhone is used for a period of time, there will be more and more software. And these software is continuously sending notification to you, which may directly affect battery consumption.
3. iOS update. The update of new iOS system will require more performance on previous iPhone models to reach more new functions and smoother effect, which leads to large battery consumption.
4. Battery health. Visit Settings > Battery > Battery Health to check your iPhone battery health. If your iPhone battery health is over 80%, it remains your iPhone battery is healthy.
Improper iPhone battery charging. Please don’t over charge your iPhone. And please don’t charge it for a whole night.
5. Cold whether. You may find that iPhone battery drains faster when it’s cold. Keep your iPhone warm to protect the battery.
Read on this tutorial to learn how to fix fast draining iPhone battery: https://all-things-about-apple.blogspot.com/2021/06/12-ways-to-fix-fast-draining-battery-on.html