iphone 13 battery draining after the 17.6.1 ios update

Here are some things to look for that come from Apple’s official page that talks about iPhone battery drain issues. 

• Did you recently update your iPhone?: If you notice that your battery life has decreased after updating your iPhone, wait a few days and then check again.
• Even though you can use your iPhone immediately after an update, certain tasks related to the update continue in the background and might affect battery life and thermal performance.
• Background Activity: Most of the app's battery usage — such as playing music or tracking location — happened while the app was active in the background. You can improve battery life by reducing your use of the app.
• No Mobile Coverage and Low Signal: Your iPhone was searching for a Wi-Fi or cellular signal or being used in a low signal environment, and this affected your device's battery life. To improve battery life, if you can, use your iPhone in a place with a strong signal. If you know you'll be in an area with no coverage for some time, enable Airplane Mode.
• Notifications: The app's notifications wake the device. To improve battery life, you can adjust the app's notifications to wake the device less often.
• Connected to Charger: The app was used only while your iPhone was charging, so the battery wasn't used.

Try and Force Restart your iPhone EXACTLY as shown below and see whether that resolves the issue:

• Press and quickly release Volume UP button
• Press and quickly release Volume DOWN button
• Press and Hold the SIDE button until an Apple logo appears and then release the Side button (Can take up to 20 seconds. (DO NOT release Side Button when invited to Slide Power OFF). 

Axel F.