Your phone battery is lying to you, and honestly, it's doing a better job of it than most people.
Here's the thing about those days when everything feels like it's on fire. Your brain taps out somewhere around the third crisis of the morning, and your phone quietly becomes your new brain. Need to remember something? Phone. Can't do basic math? Phone. Forgot what you were walking into the kitchen for? Phone. Your poor device is basically doing two jobs while getting paid nothing, which explains why it's face down and dead by 2pm.
The "planned obsolescence" crowd will tell you the phone companies are doing it on purpose. The stressed-out crowd will swear their anxiety is somehow broadcasting through their thumbs and draining the battery. Both groups are wrong, and both groups are probably exhausted.