We have the same problem with our iPhone SE! It started to behave very erratically after the iOS 14.2 update! It went from 100% to 3% over the period of 8 hours without ANY phone calls, text, or use of any apps! In other words, the phone drains the battery without user-initiated activities. Could there be hidden apps running in the background without the user's knowledge? Apple Support led us on a wild goose chase without telling us that the problem was with the update itself! After several useless conversations with Apple Support, I had to download and install a fresh OS, which wiped out everything on our phone. The tech support guy at the store told us NOT to restore the backup files, which we created prior to the OS re-installation, which was what Apple Support told us to do! Even after the OS refresh, the phone still has the battery drainage issue. A diagnostic results were good: nothing failed! But Apple Support guessed "it could be hardware problem" and wanted me to send in the phone for repair. Since its warranty has expired, it would be a waste of my money! Will Apple address the problem and fix it soon? Apple has left us with a very very bad taste in the mouth now. We're going to dump our iPhone (and all Apple products) and get an Android phone.