PSI Colours Meaning

[Alsweider]

Hello, I'm relatively new here and I noticed that the background colours of the PSIs can differ even if the displayed number is the same. A PSI of 80 can have a dark green ("Good") or a standard green ("Decent") background. The help section doesn't seem to explain this. Is this related to the Average Percentile or is it due to rounding up or rounding down the number?