That watch face does turns on the compass and heart rate monitor when the screen is on, so that won't be great for battery usage. Just to eliminate any other issues you could try an 'Install Default Apps' from the about page of the App Loader and see if the battery does drain as quickly
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Very odd about the backlight intensity. Did it always do that, or is it new? Is it possible the watch has got water inside it?
I believe that watch face is dotmatrix: https://banglejs.com/apps/#dotmatrix
That watch face does turns on the compass and heart rate monitor when the screen is on, so that won't be great for battery usage. Just to eliminate any other issues you could try an 'Install Default Apps' from the about page of the App Loader and see if the battery does drain as quickly