These lines are based on the device's vsync period (desired framerate), usually 16ms (60fps)
And represent a percentage of this period:
Green - 80%
Yellow - 100%
Red - 150%

so for 60fps they are
Green - ~13ms (~78fps)
Yellow - 16ms (60fps)
Red - 24ms (~41fps)

Source:
https://android.googlesource.com/platform/frameworks/base/+/refs/heads/main/libs/hwui/FrameInfoVisualizer.cpp?pli=1#41

so the official documentation is outdated