M5 recommends not using a brightness level above 20% when using the FastLED library (which is the library behind ESPhome's FastLED component). I'm pretty sure the reason for the recommendation is because of potential damage from heat generated by the LEDs.

I found that when I used the recommended 20% brightness and the "flicker" effect, the LEDs would sporadically turn themselves off after a few seconds. With a brightness of 25%, that doesn't happen. so that is the value that I settled on using. The exception is the "pilot_off" animation, which uses all of the blue LEDs in a blinking pattern and which might be on for several hours. It uses 20% brightness.

I originally used brightness values in the 30s for most animations, and the photos and video in this project were taken with those higher values. A side-effect of switching to 25% is that the orange color is generally a bit more red, with some orange coming in occasionally during the flicker. I could experiment with different RGB values to try to get back to more orange, but those kinds of experiments wear me out pretty fast. The colors shown for RGB values on any one of a million web page charts bear only a mild resemblance to the colors produced by M5 Atom Matrix.

The original brightness values in the pictures and video are:

•   startup: 30%
•   full_flame: 35%
•   dazzled: 35%
•   pilot_on: 25%
•   pilot_off: 50%