It looks like the AMD is the ones tagged in red, Nvidia tagged in blue, so if I'm reading it right, the blue/red is average, the black is random peaks either up or down, looks like for the majority the black is peak lows, I may be wrong but using the RX 6600 for an example it averages 122fps and at random times stutters down to 99, usually those stutters are transitional based, and usually only last a few seconds here and there if that long, purely based on what I've seen in reviews, but again I might be wrong, so don't take my word for it