I have the same problem after upgrading to IOS 14.3. I believe there are some problems in the low power mechanism. My IPhone consumes much of battery even when I am sleeping everyday... which means my alarm will not work if I didn't charge before going to bed. (sad)
Here are the evidences - https://developer.apple.com/forums/content/attachment/5ab821fe-b0ed-4804-bc03-9840d28f4e2c
Easonlai
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