Solution:[br]
Restore iPhone. Means a complete wipeout, different from the usual reset or erase. Doing that and restoring a Finder Mac iTunes backup will bring back issue still.
Thereafter, restore from iCloud backup. The only way forward. And do not let your battery drop below 20% anymore.
After I did the above, the issue went away. Just hours ago, when I inevitably had to drop the battery below 20% because I did not have my charger, the issue has come back. Hence as follows.