Might just be about decimals that arent displayed
I think it has to do with the fact that they base these ratings of numbers with more decimals, hence the reason nickelback has green and bit has yellow
maybe it's because b1t is 1.045 and nickelback 1.055 idk
Rating is more than three digits, they just round it for display. Nickelback might have 1.059 and B1t 1.053. The color itself is based on percentiles, I think green is 25 percentile, yellow is 75-25, and red is bottom 25.
If you click complete statistics you can see it's yellow as well