(1) 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).
(2) If the above does not work then - Check the battery health of your iPhone. Open Settings ➔ Battery ➔ Battery Health and let us know which percentage you see for Maximum Capacity. Also note what is written under Peak Performance. If your battery's Maximum Capacity shows a value of 80% or less, then it has gone through its lifecycle and therefore should be replaced, according to Apple.
(3) If Battery Health is fine, then - Check the available free storage space on your iPhone. Is the storage space nearly full? Do you have at least 10GB+ free storage space?
Axel F.