In the MoonBot terminal I use Mark B&W icons, why are some icons with different bars (one, two, three) next to folder names?

If you have selected black and white icons from Mark in the MoonBot terminal (Settings – User Interface, Icons: Mark B&W), you can observe the following icons next to folders:
– one bar on the icon (no active strategies in the folder, all lights off)
– two bars on the icon (the folder has several active strategies, some of the lights are lit)
– three bars on the icon (all strategies in the folder are active, all lights are on)